feat: add logging hook, rm logging from evaluation

[liran2000]

Implements: [FEATURE] Implement Logging Hook

This PR removes logging from the main evaluation code path, with a few exceptions, like unhandled errors in event handlers. These cases are printed with default slog.
It also adds a LoggingHook as per the spec link above, using slog.

logr usage is removed, but exported APIs remains for backward compatibility.

Java implementation

Closes: #284

@toddbaert @Kavindu-Dodan

[toddbaert]

@liran2000 sorry I missed this! I will review today. Looks like there's some CI failures though.

[liran2000]

@liran2000 sorry I missed this! I will review today. Looks like there's some CI failures though.

Thanks, this PR requires GO version to be upgraded to 1.21 before proceeding, hence the failures.

[toddbaert]

I've opened: #294

[toddbaert]

@liran2000 thanks so much; sorry for the wait.

#289 (comment) is my only question. Approved, but wonder what your thoughts on that are.

[toddbaert]

@liran2000 I've merged the Go 1.2.1 change, there's a few lint/CI failures.

[codecov]

Codecov Report

Attention: Patch coverage is 82.75862% with 10 lines in your changes missing coverage. Please review.

Project coverage is 82.19%. Comparing base (ddfffdd) to head (81acdf6).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
openfeature/hooks/logging_hook.go	81.63%	6 Missing and 3 partials ⚠️
openfeature/event_executor.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #289      +/-   ##
==========================================
+ Coverage   81.89%   82.19%   +0.30%     
==========================================
  Files          10       11       +1     
  Lines        1215     1219       +4     
==========================================
+ Hits          995     1002       +7     
+ Misses        199      193       -6     
- Partials       21       24       +3     

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[toddbaert]

Thanks again @liran2000