Cask::DSL: define instance variables in initialize

We're now seeing warnings related to the cask DSL surfaced by Ruby
3.4:

```
/opt/homebrew/Library/Homebrew/cask/dsl.rb:456: warning: The class
Cask::DSL reached 8 shape variations, instance variables accesses
will be slower and memory usage increased.
It is recommended to define instance variables in a consistent order,
for instance by eagerly defining them all in the #initialize method.
```

I've been working on upgrading `Cask::DSL` to `typed: strict` and
part of that involves defining all of the instance variables in the
`initialize` method, so I've extracted this part of that work as a
way of helping to resolve the aforementioned warning. This doesn't
fully resolve the warning but it addresses what it was originally
referencing, at least.

For what it's worth, this includes some type fixes but I've only
included what's necessary to pass `brew typecheck`.

Library/Homebrew/cask/dsl.rb

@@ -90,14 +90,14 @@ module Cask
       :deprecated?,
       :deprecation_date,
       :deprecation_reason,
-      :deprecation_replacement_formula,
       :deprecation_replacement_cask,
+      :deprecation_replacement_formula,
       :disable!,
       :disabled?,
       :disable_date,
       :disable_reason,
-      :disable_replacement_formula,
       :disable_replacement_cask,
+      :disable_replacement_formula,
       :discontinued?, # TODO: remove once discontinued? is removed (4.5.0)
       :livecheck,
       :livecheck_defined?,
@@ -112,18 +112,39 @@ module Cask
 
     include OnSystem::MacOSAndLinux
 
-    attr_reader :cask, :token, :deprecation_date, :deprecation_reason, :deprecation_replacement_formula,
+    attr_reader :cask, :token, :artifacts, :deprecation_date, :deprecation_reason,
-                :deprecation_replacement_cask, :disable_date, :disable_reason, :disable_replacement_formula,
+                :deprecation_replacement_cask, :deprecation_replacement_formula,
-                :disable_replacement_cask, :on_system_block_min_os
+                :disable_date, :disable_reason, :disable_replacement_cask,
+                :disable_replacement_formula, :on_system_block_min_os
 
+    sig { params(cask: Cask).void }
     def initialize(cask)
-      @cask = cask
+      @artifacts = T.let(ArtifactSet.new, ArtifactSet)
+      @called_in_on_system_block = T.let(false, T::Boolean)
+      @cask = T.let(cask, Cask)
+      @caveats = T.let(DSL::Caveats.new(cask), DSL::Caveats)
+      @depends_on = T.let(DSL::DependsOn.new, DSL::DependsOn)
       @depends_on_set_in_block = T.let(false, T::Boolean)
       @deprecated = T.let(false, T::Boolean)
+      @deprecation_date = T.let(nil, T.nilable(Date))
+      @deprecation_reason = T.let(nil, T.nilable(T.any(String, Symbol)))
+      @deprecation_replacement_cask = T.let(nil, T.nilable(String))
+      @deprecation_replacement_formula = T.let(nil, T.nilable(String))
+      @disable_date = T.let(nil, T.nilable(Date))
+      @disable_reason = T.let(nil, T.nilable(T.any(String, Symbol)))
+      @disable_replacement_cask = T.let(nil, T.nilable(String))
+      @disable_replacement_formula = T.let(nil, T.nilable(String))
       @disabled = T.let(false, T::Boolean)
+      @language_blocks = T.let({}, T::Hash[T::Array[String], Proc])
+      @language_eval = T.let(nil, T.nilable(String))
+      @livecheck = T.let(Livecheck.new(cask), Livecheck)
       @livecheck_defined = T.let(false, T::Boolean)
+      @name = T.let([], T::Array[String])
       @on_system_blocks_exist = T.let(false, T::Boolean)
       @token = cask.token
+      @on_system_block_min_os = T.let(nil, T.nilable(MacOSVersion))
+      @staged_path = T.let(nil, T.nilable(Pathname))
+      @token = T.let(cask.token, String)
     end
 
     sig { returns(T::Boolean) }
@@ -153,7 +174,6 @@ module Cask
     #
     # @api public
     def name(*args)
-      @name ||= []
       return @name if args.empty?
 
       @name.concat(args.flatten)
@@ -210,7 +230,6 @@ module Cask
       if args.empty?
         language_eval
       elsif block
-        @language_blocks ||= {}
         @language_blocks[args] = block
 
         return unless default
@@ -226,11 +245,13 @@ module Cask
     end
 
     def language_eval
-      return @language_eval if defined?(@language_eval)
+      return @language_eval unless @language_eval.nil?
 
-      return @language_eval = nil if @language_blocks.blank?
+      return @language_eval = nil if @language_blocks.empty?
 
-      raise CaskInvalidError.new(cask, "No default language specified.") if @language_blocks.default.nil?
+      if (language_blocks_default = @language_blocks.default).nil?
+        raise CaskInvalidError.new(cask, "No default language specified.")
+      end
 
       locales = cask.config.languages
                     .filter_map do |language|
@@ -241,18 +262,15 @@ module Cask
 
       locales.each do |locale|
         key = locale.detect(@language_blocks.keys)
+        next if key.nil? || (language_block = @language_blocks[key]).nil?
 
-        next if key.nil?
+        return @language_eval = language_block.call
-
-        return @language_eval = @language_blocks[key].call
       end
 
-      @language_eval = @language_blocks.default.call
+      @language_eval = language_blocks_default.call
     end
 
     def languages
-      return [] if @language_blocks.nil?
-
       @language_blocks.keys.flatten
     end
 
@@ -425,7 +443,6 @@ module Cask
     #
     # @api public
     def depends_on(**kwargs)
-      @depends_on ||= DSL::DependsOn.new
       @depends_on_set_in_block = true if @called_in_on_system_block
       return @depends_on if kwargs.empty?
 
@@ -439,7 +456,7 @@ module Cask
 
     # @api private
     def add_implicit_macos_dependency
-      return if @depends_on.present? && @depends_on.macos.present?
+      return if (cask_depends_on = @depends_on).present? && cask_depends_on.macos.present?
 
       depends_on macos: ">= :#{MacOSVersion::SYMBOLS.key MacOSVersion::SYMBOLS.values.min}"
     end
@@ -452,10 +469,6 @@ module Cask
       set_unique_stanza(:conflicts_with, kwargs.empty?) { DSL::ConflictsWith.new(**kwargs) }
     end
 
-    def artifacts
-      @artifacts ||= ArtifactSet.new
-    end
-
     sig { returns(Pathname) }
     def caskroom_path
       cask.caskroom_path
@@ -476,7 +489,6 @@ module Cask
     #
     # @api public
     def caveats(*strings, &block)
-      @caveats ||= DSL::Caveats.new(cask)
       if block
         @caveats.eval_caveats(&block)
       elsif strings.any?
@@ -500,7 +512,6 @@ module Cask
     #
     # @api public
     def livecheck(&block)
-      @livecheck ||= Livecheck.new(cask)
       return @livecheck unless block
 
       if !@cask.allow_reassignment && @livecheck_defined