feat: Add basic env var provider

[chrfwow]

This PR

Adds a very basic implementation of an env var provider

Please make sure that the repo setup is correct.

Follow-up Tasks

If we want more advanced behaviour as in the java env var provider (env var name transformation, alternative env var access logic, ...) or more tests, this can be done in a follow up PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.21%. Comparing base (144c725) to head (ce3fee1).
Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #276 +/- ##
==========================================
+ Coverage 94.00% 94.21% +0.21% 
==========================================
Files 18 20 +2 Lines 984 1020 +36 ==========================================
+ Hits 925 961 +36 
Misses 59 59 

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[toddbaert]

I'm preemptively approving, but please consider this.

[gruebel]

nice work, just found some minor stuff.

@beeme1mr can you setup the release on pypi side?

[gruebel]

ok, I think everything looks good for an initial version 🍻

[alexandraoberaigner]

Looks good to me too! 🎉