fix: fix cycle dependency between api and client

[gruebel]

This PR

• moved the api function related to hooks, evaluation context and transaction context to their dedicated module and re-exposed them, so there is no difference in the import statement, but now you can directly import them without needing to do it via openfeature.api
• I didn't find a good way to make sure we don't this again. I know of importlinter which could help, but it doesn't work on the base of the namespace package.

Related Issues

Fixes #478

[imnotjames]

I grabbed the code from this PR and as far as I can tell it resolves the issue I was running into

[codecov]

Codecov Report

Attention: Patch coverage is 97.87234% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.44%. Comparing base (e61b69b) to head (2148972).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
openfeature/evaluation_context/__init__.py	95.45%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #480   +/-   ##
=======================================
  Coverage   97.44%   97.44%           
=======================================
  Files          37       37           
  Lines        1759     1761    +2     
=======================================
+ Hits         1714     1716    +2     
  Misses         45       45           

Flag	Coverage Δ
unittests	97.44% <97.87%> (+<0.01%)	⬆️

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