feat(kuma-dp): add function to find default CA

[lukidzi]

xrel: #10238

Checklist prior to review

I added an option to propagate information about the default OS CA certificate in a bootstrap request from kuma-dp.

• a user can provide a path to the certificate when it's not a default one for the OS
• if the cert path is not provided we are scanning default paths based on the https://golang.org/src/crypto/x509/root_linux.go
• propagate the information in metadata

• Link 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 a image registry) and it will work on Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS --
• Tests (Unit test, E2E tests, manual test on universal and k8s) --
  • Don't forget ci/ labels to run additional/fewer tests
• Do you need to update UPGRADE.md? --
• 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) --