feat: adopt new HTTP layer from OpenAPIRuntime and migrate Functions to it

[grdsdev]

What kind of change does this PR introduce?

Close #634

What is the current behavior?

Please link any relevant issues here.

What is the new behavior?

Feel free to include screenshots if it includes visual changes.

Additional context

Add any other context or screenshots.

[coveralls]

Pull Request Test Coverage Report for Build 16836901907

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 130 of 185 (70.27%) changed or added relevant lines in 5 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.4%) to 77.009%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
Sources/Supabase/AuthClientTransport.swift	0	7	0.0%
Sources/Helpers/HTTP/Client.swift	34	45	75.56%
Sources/Functions/FunctionsClient.swift	75	92	81.52%
Sources/Helpers/HTTP/LoggingMiddleware.swift	3	23	13.04%

Files with Coverage Reduction	New Missed Lines	%
Sources/Functions/FunctionsClient.swift	3	87.34%

Totals
Change from base Build 16830846344:	-0.4%
Covered Lines:	5557
Relevant Lines:	7216

---

💛 - Coveralls