Ohttp middleware

[zealsham]

This pr addresses a part of #941 consigned with implementing an ohttp gateway middleware.

too many merge conflicts while trying to rebase #1306 , so i decied to abandon that all together and start a new one.
i had gemini help with writing most of the tests .

Pull Request Checklist

Please confirm the following before requesting review:

• I have disclosed my use of
  AI
  in the body of this PR.
• I have read CONTRIBUTING.md and rebased my branch to produce hygienic commits.

[coveralls]

Coverage Report for CI Build 27063675194

Coverage increased (+0.1%) to 85.474%

Details

• Coverage increased (+0.1%) from the base build.
• Patch coverage: 14 uncovered changes across 3 files (282 of 296 lines covered, 95.27%).
• 2 coverage regressions across 1 file.

Uncovered Changes

File	Changed	Covered	%
payjoin-mailroom/src/ohttp_gateway/error.rs	21	13	61.9%
payjoin-mailroom/src/ohttp_gateway/mod.rs	246	242	98.37%
payjoin-mailroom/src/directory.rs	25	23	92.0%
Total (4 files)	296	282	95.27%

Coverage Regressions

2 previously-covered lines in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
payjoin-mailroom/src/directory.rs	2	86.11%

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Coverage Stats

Relevant Lines:	14842
Covered Lines:	12686
Line Coverage:	85.47%
Coverage Strength:	367.87 hits per line

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💛 - Coveralls

[DanGould]

This is looking pretty good to me, so I'm bumping it, but prioritizing #1610

[zealsham]

This is looking pretty good to me, so I'm bumping it, but prioritizing #1610

Sure! , I’ll do rebase once #1610 goes in and fix any conflicts