devel/rubygem-yard-sorbet: Add rubygem-yard-sorbet 0.9.0

yard-sorbet is a YARD plugin that parses Sorbet type annotations.

Features:
- Attaches existing documentation to methods and attributes that follow sig
  declarations. (This information is otherwise discarded.)
- Translates sig type signatures into corresponding YARD tags
- Generates method definitions from T::Struct fields
- Generates constant definitions from T::Enum enums
- Modules marked abstract! or interface! are tagged @abstract
- Modules using mixes_in_class_methods will attach class methods
- Merges sigs in rbi files with source code documentation (rbi files must come
  after source code in yard configuration)