🌱 Add option to skip rancher pre-requisites

[Danil-Grigorev]

What this PR does / why we need it:
This change should allow to install turtles in development scenario without dependency on rancher, for the expense of added requirement to patch the embedded-cluster-api feature gate manually.

This can be done by specifying --set rancherTurtles.rancherInstalled=false flag.

Deletion will need to be performed according to https://turtles.docs.rancher.com/getting-started/uninstall_turtles

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #627

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests

[hardys]

Thanks for working on this @Danil-Grigorev - the change looks good to me, although it's now clear we could potentially use the existing features.embedded-capi API to achieve the same thing, unless we expect any other dependencies on Rancher in the pre-install phase.

Note for other reviewers the use-case behind #627 is we want to deploy Rancher and Rancher Turtles via the RKE2 helm controller - in this situation ordering of the helm installs cannot be controlled, so you end up reliant on retries, so we must ensure the turtles chart can either install, or fail and be uninstalled, in the case where Rancher is not yet installed.

A related issue is in the pre-delete hook we assume the capiproviders CRD exists, and the hook fails otherwise - IMO for a robust fix we should consider making the pre-delete hook fail gracefully in this scenario (e.g check if the crd exists, and exit without any error if it's missing), but that could be considered as a follow-up perhaps.

[furkatgofurov7]

@Danil-Grigorev can we also update the turtles docs regarding this, since current docs have rancher listed as pre-requisite and has a dedicated chapter for installing it before Turtles? I believe this provides a fix for the specific use case edge team has, but I suggest we need to be super clear on what are the consequences if this option is enabled.