[Phase 2][Post GA][YSQL] Feature: Automatic pull-out of tables from colocation

[thinknirmal]

Jira Link: DB-559
Would be nice to have a feature that automatically opts-out tables from colocation once they cross a threshold. This would mean that every database could be a colocated database by default, and then tables moving into their own tablets as they grow.

This would push Yugabyte one step further into a truly self-optimising database.

[mgrosso]

An application I have in mind with a very large number of tables would only be feasible with this feature, and would be combined with colocation defined at the database and schema levels.

Also needs #4463 or the ability to control the splitting parameters so the schemas colocate out of the database before their larger tables un-colocate themselves.