Controller to perform defragmentation for etcd.

Goal

• As per bug https://issues.redhat.com/browse/OCPBUGS-12150 , etcd defragmentation and compaction should be performed as needed for HA deployments.

Why is this important?

• It is possible for etcd to consume a lot of disk space and have poor performance if we do not do routine maintenance of etcd.  

Scenarios

• As etcd grows in key/value pairs, the database expands.  If they are deleted, the space is never released from disk.  etcd will reuse these slots if a new entry will fit in them.  However over time key/value space will become inefficient and require compaction/defragmentation to free up extra space.
• We will have a controller that runs as a separate process from control-plane-operator, but spawned from it to perform these operations.

Acceptance Criteria

• Dev - Has a valid enhancement if necessary
• CI - MUST be running successfully with tests automated
• QE - covered in Polarion test plan and tests implemented

Done Checklist

• CI - CI is running, tests are automated and merged.
• Release Technical Enablement <link to Feature Enablement Presentation>
• DEV - Upstream documentation merged: <link to meaningful PR or GitHub Issue>
• DEV - Enhancement merged: <link to meaningful PR or GitHub Issue>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - Downstream documentation merged: <link to meaningful PR>