Add HTTP Expectations

See this comment from @darobin, similarly to #17 we should prepare for HTTP expectations as well.

> The one (relatively small) thing I would flag is that you seem to be relying on string matching (equals/contains) but a lot of these values can be wilder (eg. case insensitive, there may be spaces, the value might have to be anchored at the start of the string, etc.). If your HTTP library normalises values, this probably helps a fair bit (worth checking), but it's like that quite a few checks will need to go to regex land. This isn't a big deal and not a problem for the framework, I'm just flagging it as a potential problem that jumped out, probably worth addressing before too many tests are written.

reference: https://github.com/ipfs/gateway-conformance/issues/2#issuecomment-1471971928

## Plan

We should tackle this after all the kubo sharness tests have been ported

- [ ] Look into libraries that might provide similar features (in Go or other languages, we can always reuse their patterns)
- [ ] Then go through the fields, headers, matching, etc. And implement more reliable matchers.