test: add test for comparing rendered content vs public gateway

[SgtPooki]

We want to ensure sw-gateway is rendering content the same as our current public gateways.

steps:

• decide on CIDs to test
• write e2e test that will take snapshot of rendered sw-gateway response and compare vs rendered public gateway(ipfs.io/dweb.link) response

[lidel]

There are too many things, for this to bring any meaningful confidence, we need to reimplement a chunk of conformance test suite, so maybe reframe this to be a basic E2E smoke test?

We could pick most impactful tests to catch regressions, my E2E shortlist would be:

• JPG or JSON directly (/ipfs/QmbWqxBEKC3P8tqsKc98xmWNzrzDtRLMiMPL8wBuTGsMnR)
• /ipfs/dir-cid redirecting to /ipfs/dir-cid/ and confirming URL ends with trailing slash
• /ipfs/dir-cid/ returns HTML from with /ipfs/dir-cid/index.html (normal + HAMT)
• TBD: dir listing /ipfs/dir-cid/ for directory without index.html (normal + HAMT)
  • this is generated, so we can't expect pixel-perfect copy, all we care is if links to expected child files exist

Failing any of those is very bad. Other things will have limited blast radius.