chore: add integration tests

[nadiamoe]

This PR adds an integration test suite to crocochrome, which should help catch succinct errors in the crocochrome setup, such as misconfigurations of chromium, permissions, capabilities, etc. All other tests in the codebase run a simple script instead of real chromium.

The suite roughly works like this:

• It builds the crocochrome container using the Dockerfile, and starts it
• It starts a paused k6 container (grafana/k6, updated by renovate so we can notice if something breaks)
• For each test script in the test case:
  • Creates a new session using crocochrome API
  • Execs into the k6 container and uses it to run the script against the WS url provided by crocochrome
  • Check the return code of k6 is 0, and that the string error does not appear in k6 logs
  • Deletes the session using crocochrome API

As normal, if any of these steps fail, the test fails.

All is done with testcontainers in go, so this test will normal run as part of go test without any special configuration, and should work everywhere as long as docker is available. As crocochrome is not multiarch though, running this test on arm might be very slow or not work at all. If this is the case, this test can be skipped by setting the env var TEST_INTEGRATION_SKIP to any non-empty value.

[The-9880]

Overall LGTM, a few small comments

[The-9880]

Suggested change

	// buildContainer builds the container image for sm-k6-runner by running `docker` commands, generating an image on the
	// buildContainer builds the container image for crocochrome by running `docker` commands, generating an image on the

[nadiamoe]

Hehe, this is a copypaste and it shows. Good catch!

[The-9880]

nit: Not a big deal, but the doc comment suggests we call this before the error check as a defer.

[The-9880]

Also on L91

[nadiamoe]

I have done the "before error check" part, but the defer one feels like an error in the docs to me: CleanupContainer is already wrapping the remove call in t.Cleanup, there doesn't seem to be any point to defer it further: https://github.com/testcontainers/testcontainers-go/blob/add4ac3f019b773ae08c1af05f57554ba6819430/testing.go#L73

[The-9880]

Is it worth adding a step to delete the image after the integration test suite runs?

[nadiamoe]

I went ahead and implemented this, but after doing so I'm not sure there is really a point to it.
Even if I run docker rmi ..., all the build cache and intermediate layers will remain, so I wonder what is the point of removing the tag if the users would need to garbage-collect the things that actually take space on its own.

[The-9880]

Good point, I don't think it's necessary either :)

[nadiamoe]

Thanks for the review @The-9880 ! Will apply the suggested changes on monday :)

[nadiamoe]

Hehe, this is a copypaste and it shows. Good catch!