Add x-region support

[juancarlospaco]

What kind of change does this PR introduce?

• Add x-region support, which allows for the specification of an edge region.
• Tiny code optimization/reordering, check for invoke_options only once.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes missing coverage. Please review.

Project coverage is 86.29%. Comparing base (a809e98) to head (0588be9).
Report is 51 commits behind head on main.

Files	Patch %	Lines
supabase_functions/_async/functions_client.py	88.88%	1 Missing ⚠️
supabase_functions/_sync/functions_client.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #126      +/-   ##
==========================================
+ Coverage   85.21%   86.29%   +1.07%     
==========================================
  Files           7        7              
  Lines         115      124       +9     
==========================================
+ Hits           98      107       +9     
  Misses         17       17              

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