feat: dedicated target per gateway specification and smaller-range groups

[hacdias]

Close #74. Close #78. This PR does the following:

• Defines the existing specs in https://specs.ipfs.tech/http-gateways/
• Some of the specs are decoupled in smaller sub-specifications. They can be enabled and disabled individually.
  • E.g. +TrustlessGateway -TrustlessGatewayIPNS will run CARs and RAW tests.
• Moves files around to make them more or less match the current specifications.
• Adds new tests for /ipfs/{cid}?format=raw
• @laurentsenta I kept in comment the name of the files were tests came from such that you can still go check if all tests were ported from sharness.
• Unexported Run such that all tests are attached to some specification.

What this PR is not:

• A perfect separation of tests per spec. There's some tests that are ambiguous and it's most likely because we always assumed "oh, it's Kubo and it can do everything".
• Did not change the name of the fixture files.

Some notes:

• Most of the DNSLink Gateway (https://specs.ipfs.tech/http-gateways/dnslink-gateway) tests are not enabled yet.
• I want to make it clear that the DNSLink inlining in subdomain gateways ({ dnslink-fqdn-inline }.ipns.{domain}) is not a DNSLink gateway.

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I will also need some feedback here from @galargh @lidel @laurentsenta. Ideally, we should have all specifications defined and some (all?) would run by default. Then the user can tinker with it.

I think the most complicated part is defining subsets. For example: Trustless Gateway is a subset of the Path Gateway. Therefore, if I run the tests for the Path Gateway, I should also be running the Trustless Gateway tests, and so on and so forth.

[hacdias]

The PR is ready to looked at. Note that I updated the PR description with all the new information. It seems that the tests are stuck "provisioning Kubo gateway" and I'm not sure what's wrong as I did not change any of the fixtures.

[laurentsenta]

Code LGTM, investigating why CI breaks.

[lidel]

Thank you @hacdias, lgtm!

I've dropped some unrelated TODOs for future PRs (things I've noticed while looking at this PR), but as for this PR, it's only missing docs (outline of mvp readme below).

Ideally, we should have all specifications defined and some (all?) would run by default. Then the user can tinker with it.

Yes, by default we run all, and then user can adjust, if required.

I think this PR should also include section in README about this.
Questions we want to have answered there:

• what is run by default (all mature tests)
• opt-outs
  • how user can skip specific test group (example: disable subdomain and dnslink gateways)
  • how user can skip individual test (example: -skip is used in Kubo CI here but not documented anywhere in readme atm, and Saturn folks thought it is not possible)
• how user can disable all tests and run only specific group
  • including example how to run only the trustless raw+car but without ipns will be enough

addressed