add leader election and multi replica support

[OliverMKing]

Description

Adds full leader election and multi replica support to the operator. This is a requirement for resiliency through a PDB and is needed as clusters move towards more automatic upgrade scenarios. A PDB + multiple replicas is the best way to ensure the operator continues to function after a cluster upgrade (and really throughout all scenarios).

You can see below how this is an active-passive HA model where only the replica with the leader election lock performs actions.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tested locally + e2e. This change is really just taking advantage of built-in controller runtime features which is a well tested and well established k8s library.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[OliverMKing]

/ok-to-test sha=63d1a5c

[OliverMKing]

/ok-to-test sha=63d1a5c

[davidgamero]

lgtm

[OliverMKing]

/ok-to-test sha=63d1a5c

[OliverMKing]

/ok-to-test sha=70daac1