Options: Add #to_s method

`Options` objects are converted to a string in some circumstances but
this produces output like `#<Options:0x0000000102592c90>`.

For example, formulae.brew.sh contains analytics entries with
incomprehensible names like `adns #<Options:0x0000000102592c90>`.
This shortcoming is apparent when compared to other entries like
`adns --HEAD`.

The `Option` class has a `#to_s` method that returns the `flag`, so
this commit simply adds an `Options#to_s` method that calls `#to_s`
on each `Option` object in `@options` and joins them using spaces.
This should produce more useful output when an `Options` object is
converted to a string (e.g., `--first --second`).

Library/Homebrew/options.rb

@@ -145,6 +145,11 @@ class Options
 
   alias to_ary to_a
 
+  sig { returns(String) }
+  def to_s
+    @options.map(&:to_s).join(" ")
+  end
+
   sig { returns(String) }
   def inspect
     "#<#{self.class.name}: #{to_a.inspect}>"

Library/Homebrew/test/options_spec.rb

@@ -90,6 +90,14 @@ describe Options do
     expect(described_class.create(array).sort).to eq([option1, option2].sort)
   end
 
+  specify "#to_s" do
+    expect(options.to_s).to eq("")
+    options << Option.new("first")
+    expect(options.to_s).to eq("--first")
+    options << Option.new("second")
+    expect(options.to_s).to eq("--first --second")
+  end
+
   specify "#inspect" do
     expect(options.inspect).to eq("#<Options: []>")
     options << Option.new("foo")