feat(bootstrap): support customizing corefile template from kuma-cp

[jijiechen]

Checklist prior to review

• Link to relevant issue as well as docs and UI issues
  • Put coredns configuration in a configmap #8119
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as a image registry) and it will work on Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS
  • Should not block as it's adding a new feature.
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Added
  • Don't forget ci/ labels to run additional/fewer tests
    • Should run normally
• Do you need to update UPGRADE.md?
  • No, it's compatible with old versions
• 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)
  • No backport needed

[lahabana]

No need for the label :)

[jakubdyszkiewicz]

Nice contrib!

Can you also add this new setting to pkg/config/app/kuma-cp/kuma-cp.defaults.yaml ?

[jijiechen]

I'm still working on passing the E2E tests

[jijiechen]

The E2E tests are passing.