feat(dns): embedded DNS server instead of coreDNS

[lahabana]

Motivation

Add an embedded DNS server that resolves mesh local hostnames.
This feature is disabled by default and needs to be enabled with kuma_dns_proxy_port on DPs in universal to a non 0 value or simply with kuma_runtime_kubernetes_injector_builtin_dns_experimental_proxy =true on CP in Kubernetes (this leverages sidecar injection).

Implementation information

We leveraged the same system as MeshMetric. The DNS map is exposed in the _kuma:dynamicconfig listener, we poll this from the DP at a set frequency and reload the data.

We improved the whole configfetcher to make it reusable across different components. We also setup the endpoint so that it works with etag caching while avoids unnecessary reloading and processing, we can therefore refresh the configs more quickly as well.

For the moment I added a new matrix for e2e test. If this is stable I'll switch the default.

[lahabana]

I've made a few separate commits as this is a bit of a mouthful

[github-actions]

Reviewer Checklist

🔍 Each of these sections need to be checked by the reviewer of the PR 🔍:
If something doesn't apply please check the box and add a justification if the reason is non obvious.

• Is the PR title satisfactory? Is this part of a larger feature and should be grouped using > Changelog?
• PR description is clear and complete. It Links to relevant issue as well as docs and UI issues
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as an image registry)
• IPv6 is taken into account (.e.g: no string concatenation of host port)
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Don't forget ci/ labels to run additional/fewer tests
• Does this contain a change that needs to be notified to users? In this case, UPGRADE.md should be updated.
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label)

[slonka]

In general looks promising, a bunch of questions and nitpicks. Also would love to see a simple test checking integration with a DNS client.

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• Is the PR title satisfactory? Is this part of a larger feature and should be grouped using > Changelog?
• PR description is clear and complete. It Links to relevant issue as well as docs and UI issues
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as an image registry)
• IPv6 is taken into account (.e.g: no string concatenation of host port)
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Don't forget ci/ labels to run additional/fewer tests
• Does this contain a change that needs to be notified to users? In this case, UPGRADE.md should be updated.
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label)

[lahabana]

@lobkovilya pushed a new commit which simplifies the handler API as it doesn't deal with shutdowns anymore (that's what components are for)

[slonka]

Oh, did not notice that the tests are failing.