K8SPXC-1358: Add unsafe flags

[egegunes]

CHANGE DESCRIPTION

These changes streamlines unsafe configurations with other operators. After these users will have the possibility to granularly control unsafe configurations. New flags are:

unsafeFlags:
  tls: Allow disabling TLS
  pxcSize: Allow deploying less than 3 PXC pods
  proxySize: Allow deploying less than 2 Proxy pods
  backupIfUnhealthy: Allow running backups on an unready cluster

This PR also introduces spec.tls.enabled field to enable/disable TLS.

CHECKLIST

Jira

• [x] Is the Jira ticket created and referenced properly?
• [x] Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• [x] Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• [x] Is an E2E test/test case added for the new feature/change?
• [x] Are unit tests added where appropriate?
• [x] Are OpenShift compare files changed for E2E tests (compare/*-oc.yml)?

Config/Logging/Testability

• [x] Are all needed new/changed options added to default YAML files?
• [x] Did we add proper logging messages for operator actions?
• [x] Did we ensure compatibility with the previous version or cluster upgrade process?
• [x] Does the change support oldest and newest supported PXC version?
• [x] Does the change support oldest and newest supported Kubernetes version?

[JNKPercona]

Test name	Status
affinity-8-0	passed
auto-tuning-8-0	passed
cross-site-8-0	passed
demand-backup-cloud-8-0	passed
demand-backup-encrypted-with-tls-8-0	passed
demand-backup-8-0	passed
haproxy-5-7	passed
haproxy-8-0	passed
init-deploy-5-7	passed
init-deploy-8-0	passed
limits-8-0	passed
monitoring-2-0-8-0	passed
one-pod-5-7	passed
one-pod-8-0	passed
pitr-8-0	passed
pitr-gap-errors-8-0	passed
proxy-protocol-8-0	passed
proxysql-sidecar-res-limits-8-0	passed
pvc-resize-5-7	passed
pvc-resize-8-0	passed
recreate-8-0	passed
restore-to-encrypted-cluster-8-0	passed
scaling-proxysql-8-0	passed
scaling-8-0	passed
scheduled-backup-5-7	passed
scheduled-backup-8-0	passed
security-context-8-0	passed
smart-update1-8-0	passed
smart-update2-8-0	passed
storage-8-0	passed
tls-issue-cert-manager-ref-8-0	passed
tls-issue-cert-manager-8-0	passed
tls-issue-self-8-0	passed
upgrade-consistency-8-0	passed
upgrade-haproxy-5-7	passed
upgrade-haproxy-8-0	passed
upgrade-proxysql-5-7	passed
upgrade-proxysql-8-0	passed
users-5-7	passed
users-8-0	passed
validation-hook-8-0	passed
We run 41 out of 41

commit: https://github.com/percona/percona-xtradb-cluster-operator/pull/1744/commits/e5380e648441e51dea2634ba3475a2ee39fa1fdb image: perconalab/percona-xtradb-cluster-operator:PR-1744-e5380e64