chore: use correct term "domain" instead of name/clientName in code

[warber]

This PR

This PR ensures consistent usage of the term "domain" throughout the codebase, replacing instances of "name," "clientName," and similar terms.

[toddbaert]

This looks right to me - my only concern with any of this is that it might be breaking, but I can't see anything that's exposed publicly which is changing.

[codecov]

Codecov Report

Attention: Patch coverage is 90.62500% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.86%. Comparing base (96d86ba) to head (85a2b68).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
openfeature/client.go	72.72%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #305   +/-   ##
=======================================
  Coverage   86.86%   86.86%           
=======================================
  Files          12       12           
  Lines        1370     1370           
=======================================
  Hits         1190     1190           
  Misses        156      156           
  Partials       24       24           

Flag	Coverage Δ
e2e	86.86% <90.62%> (ø)
unit	86.86% <90.62%> (ø)

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