CI: Improve actions/setup workflow

[ByteOtter]

What this PR does / why we need it:
Expands the existing setup actions with logic that skips python installation when python is already installed and sets the caching method depending on the lockfile type (pip for requirements.txt and poetry for poetry.lock; If no lockfile is found, an empty requirements.txt is created and caching type set to pip)

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

[NotTheEvilOne]

We should support outputs for this action. E.g.:

outputs:
  cache_type:
    description: "Detected Python cache strategy."
    value: ${{ steps.lockfile.outputs.cache_type }}

[ByteOtter]

We should support outputs for this action. E.g.:

outputs:
  cache_type:
    description: "Detected Python cache strategy."
    value: ${{ steps.lockfile.outputs.cache_type }}

Did just that with the latest commit. cache_type should now be accessible from actions that use this one.

[NotTheEvilOne]

If I remember correctly each GitHub runner has an Python instance installed. We could not determine if the expected version is installed in this case. We might need to reconsider (support input for Python version and check for that version) or can't skip setup-python calls unfortunately.

[ByteOtter]

Hmm I think in that case we should remove that skipping of setup-python .. I think otherwise it's just going to get messy without really much of a benefit in my view.

[ByteOtter]

Currently encountering this error right here:

Error: Unable to locate executable file: poetry. Please verify either the file path exists or the file can be found within a directory specified by the PATH environment variable. Also check the file mode to verify the file is executable.

Which means that at the point setup is running, setup-python expects poetry to be installed, when it detects a poetry.lock in order to inspect the cache. To fix this, we could move the install-poetry step into setup as well.

[NotTheEvilOne]

Different from pip which setup-python provides automatically you should be right in installing poetry if cache_type matches. In this case we should most likely rename it to something like package_tool?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.00%. Comparing base (b305d15) to head (8759217).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #156   +/-   ##
=======================================
  Coverage   63.00%   63.00%           
=======================================
  Files          27       27           
  Lines        1192     1192           
=======================================
  Hits          751      751           
  Misses        441      441           

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[NotTheEvilOne]

LGTM