Add RBS files for sinatra and sinatra-contrib gems

[euglena1215]

Generated initial RBS files using the rbs prototype rb command, and added type definitions for both the Sinatra core and contributed extensions.

https://github.com/sinatra/sinatra/tree/v4.0.0

I have set myself as the reviewer for this change because I believe the sinatra gem is an important and widely-used web framework. However, I am not very familiar with sinatra, so if there is someone who uses sinatra regularly and is motivated to maintain these type definitions, I would appreciate it if they could take over the reviewer role.

[github-actions[bot]]

@euglena1215 Thanks for your contribution!

Please follow the instructions below for each change. See also: https://github.com/ruby/gem_rbs_collection/blob/main/docs/CONTRIBUTING.md

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• /merge: Merge this PR if CI passes

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sinatra-contrib

This RBS files are newly added.

You can merge this PR immediately if the CI passes. Just comment /merge to merge this PR.

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sinatra

This RBS files are newly added.

You can merge this PR immediately if the CI passes. Just comment /merge to merge this PR.

[euglena1215]

/merge