feat: allow rbac to pe externally provisioned

[lsoica]

Description

In case of a cluster tenant that is not allowed to apply cluster wide resources, the redis operator helm chart cannot be installed as the cluster role and cluster role binding cannot be applied and the chart has no option to disable those resources. Instead, for such scenarios, allow the user to handle rbac provisioning outside of the chart and only link to an externally provisioned service account.

Fixes #1004

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• [ x] Tests have been added/modified and all tests pass.
• [ x] Functionality/bugs have been confirmed to be unchanged or fixed.
• [ x] I have performed a self-review of my own code.
• [ x] Documentation has been updated or added where necessary.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 45.85%. Comparing base (d121d86) to head (3800cdf). Report is 80 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1005 +/- ## =========================================== + Coverage 35.20% 45.85% +10.64% =========================================== Files 19 20 +1 Lines 3213 2687 -526 =========================================== + Hits 1131 1232 +101 + Misses 2015 1380 -635 - Partials 67 75 +8 ```

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