HMC graceful removal

[Kshatrix]

HMC has to remove itself without any extra manual steps required.

Expectations:

• HMC cleanup can be initiated with Management object removal.
• HMC controller should remove all components installed by HMC and itself in the end.
• Some admission verifications have to be added to prevent unintentional removal.

Related issues:

• Forbid Management object deletion #139
• Split Management Reconcile into Update and Delete #164
• Remove associated helm releases when Management deletion is requested #174
• Management object should be automatically created only once #175
• Don't keep cert-manager CRDs after HMC chart removal #192
• Document HMC removal procedure #194