Add cache-mode option to control cache usage

[alsutton]

Description:
Introduces the optional cache-mode input, which allows workflows to have read-only and write-only caches, as well as
the default read-write caches.

This can reduce workflow runtime for situations, such as PRs, where the build artifacts may be disposable and of little use to other workflow runs, because PRs on the main branch can create the cache (using write or both mode), and PRs can build using that cache without polluting it with PR revision specific build output (using read mode)

Related issue:
#267

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[dmitry-shibanov]

I'm going to close the pull request because the initial issue was closed.