Introduce cache-hit output

[dhvcc]

Description:
I'd like to propose adding a new output called cache-hit (like in actions/cache) to show whether dependency cache was hit.

Justification:
Since this action utilizes caching mechanic I think it would be needed to have this meta data in output since we can't access internal steps from outside.
This would be helpful if, for example, we need add stuff to PATH if this cache was hit. Another example is when you want to do optional poetry install, because there's no lock file and poetry will first try to resolve even if deps are there.

Are you willing to submit a PR?
Yes, for sure.

[dmitry-shibanov]

Hello @dhvcc. Thank you for your proposal. I think this enhancement can be implemented. If you're willing to contribute, please feel free to prepare a pull request.

[dhvcc]

@dmitry-shibanov thanks for the reply! I will take a look at the code and try to craft something today

[dhvcc]

Just as an addition - perhaps this type of output may be usefull in other setup-* workflows? I've checked an saw only setup-node providing the same output