sorbet: add compat files to true

Set the following files to true in sorbet/files.yaml:
- ./compat/extend/nil.rb
- ./compat/extend/string.rb
- ./compat/formula.rb
- ./compat/os/mac.rb

Library/Homebrew/sorbet/files.yaml

@@ -457,13 +457,8 @@ false:
   - ./cask/dsl/version.rb
   - ./cask/topological_hash.rb
   - ./cmd/cask.rb
-  - ./compat/extend/nil.rb
-  - ./compat/extend/string.rb
-  - ./compat/formula.rb
   - ./compat/language/haskell.rb
   - ./compat/language/java.rb
-  - ./compat/os/mac.rb
-  - ./dependable.rb
   - ./extend/git_repository.rb
   - ./extend/hash_validator.rb
   - ./extend/io.rb
@@ -841,6 +836,10 @@ true:
   - ./cask/url.rb
   - ./checksum.rb
   - ./cleaner.rb
+  - ./compat/extend/nil.rb
+  - ./compat/extend/string.rb
+  - ./compat/formula.rb
+  - ./compat/os/mac.rb
   - ./compilers.rb
   - ./config.rb
   - ./dependency_collector.rb

Library/Homebrew/sorbet/rbi/homebrew.rbi

@@ -12,3 +12,32 @@ module Language::Perl::Shebang
   include Kernel
 end
 
+module Dependable
+  def tags; end
+end
+
+class Formula
+  module Compat
+    include Kernel
+
+    def latest_version_installed?; end
+
+    def active_spec; end
+
+    def patches; end
+  end
+end
+
+class NilClass
+  module Compat
+    include Kernel
+  end
+end
+
+class String
+  module Compat
+    include Kernel
+
+    def chomp; end
+  end
+end

Library/Homebrew/sorbet/rbi/os.rbi

@@ -12,3 +12,11 @@ module OS
     include Kernel
   end
 end
+
+module OS::Mac
+  class << self
+    module Compat
+      include Kernel
+    end
+  end
+end