Add command spoom srb sigs translate to translate RBI signatures into RBS comments

[Morriar]

Consider the following file.rb:

# typed: strict

class Foo
  sig { returns(String) }
  attr_reader :x

  sig { params(x: String).void }
  def initialize(x)
    @x = x
  end
end

We can translate the RBI signatures it contains using the introduced Spoom command:

$ spoom srb sigs translate file.rb

Wich will update the file contents as follows:

# typed: strict

class Foo
  #: String
  attr_reader :x

  #: (String x) -> void
  def initialize(x)
    @x = x
  end
end

[paracycle]

I think this complexity wrt to UTF-16 codepoints was only about the fact that VS Code only considers UTF-16 but our code is in UTF-8.

I am not sure if we need the same complexity here. We should be able to treat it as a string of codepoints (or even bytes).

[paracycle]

How do you know that the source is UTF-8?

[paracycle]

Shouldn't this be:

Suggested change

	scanner = Scanner.new(ruby_contents, Encoding::UTF_8)
	scanner = Scanner.new(ruby_contents, ruby_contents.encoding)