feat!: use extractor pattern for request handlers

[m4tx]

This is a massive change and the transition probably isn't even fully done yet. This should be a good starting point, though.

The remaining work includes:

• Removing more of the RequestExt trait
• Creating IntoResponse trait so that the consumers can return other types than cot::Result<Response>
• More work on maintaining consistency in the API

Note that this is a (quite big) breaking change, mostly because it removes a lot of methods from the RequestExt trait.

This change is needed to implement automatic OpenAPI spec generation in #159.

[codecov]

Codecov Report

Attention: Patch coverage is 83.22521% with 181 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cot/src/admin.rs	0.00%	72 Missing ⚠️
cot/src/handler.rs	52.38%	13 Missing and 7 partials ⚠️
cot/src/auth.rs	91.97%	4 Missing and 11 partials ⚠️
cot/src/db.rs	28.57%	15 Missing ⚠️
cot/src/request/extractors.rs	94.20%	2 Missing and 10 partials ⚠️
cot/src/middleware.rs	91.91%	7 Missing and 4 partials ⚠️
cot/src/project.rs	83.87%	10 Missing ⚠️
cot/src/request.rs	96.55%	6 Missing and 1 partial ⚠️
cot/src/router.rs	80.64%	6 Missing ⚠️
cot/src/test.rs	87.50%	4 Missing ⚠️
... and 5 more

Flag	Coverage Δ
rust	81.65% <83.22%> (+0.54%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cot-macros/src/lib.rs	95.91% <ø> (ø)
cot/src/config.rs	86.90% <100.00%> (-0.74%)	⬇️
cot/src/error.rs	88.75% <ø> (ø)
cot/src/request/path_params_deserializer.rs	64.46% <ø> (ø)
cot/src/static_files.rs	93.80% <100.00%> (+0.07%)	⬆️
cot/src/cli.rs	80.74% <50.00%> (-0.41%)	⬇️
cot/src/response.rs	97.26% <85.71%> (+0.24%)	⬆️
cot/src/auth/db.rs	77.60% <60.00%> (+0.12%)	⬆️
cot/src/form.rs	67.00% <95.34%> (+19.54%)	⬆️
cot/src/session.rs	82.35% <82.35%> (ø)
... and 10 more

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[seqre]

At the very end, you should go over the generated tests and remove the pointless comments.

[seqre]

Great work! Hit the Codecov's limit of 81.1% and I'll gladly approve

[seqre]

👌🎉