[platform] Improving day 2 operations of Yugabyte Platform

[rkarthik007]

This task captures various improvements in day 2 operations of Yugabyte Platform.

Note that Yugabyte Platform is a commercial product.

Security

✅ Enable simple role based access (admin and read-only user)
✅ Support encryption (both on the wire and at rest)
✅ Support OAuth2/OIDC based authentication
✅ Web-based security (Qualys) scan for Platform should pass
✅ Platform should not need to be installed as root user

High availability

✅ Enable backup and restore of yb platform
✅ Enable backups of metric data which uses Prometheus.
⬜️ Store all the filesystem metadata into the DB.
⬜️ Enable the ability to specify an external PostgreSQL DB for the platform

Metrics and reporting

⬜️ Metrics for num connections to cluster
⬜️ Add administration information such as live queries per node and slow queries

Operational improvements

✅ Ability to perform nightly backups of managed YB universes
⬜️ Improvements to DB flag updates (change dynamic flags without a rolling restart)
⬜️ Ability to perform software upgrades and DB flag changes in one step
⬜️ Enable built-in load balancer for non-k8s YSQL deployments in the supported public clouds

Usability improvements

⬜️ Provide a DB checklist in the overview page to highlight what is turned on and what is not ex. DB Security, Encryption, Backup, Health check etc.
⬜️ Ability to update the universe state (from error to ready on-demand)

Aha! Link: https://yugabyte-test.aha.io/features/PLATFORM-452