WL#2498: Support Add/Drop/Reorganise/Coalesce Partition in NDB kernel

Affects: Server-7.1   —   Status: On-Hold   —   Priority: Medium

Support ADD/DROP Partition on RANGE/LIST partitions
Support ADD/COALESCE Partition on HASH partitions

This feature needs support in the NDB kernel to be useful for MySQL Cluster.

The work includes

Same 3-step approach as used in the MySQL Server for partition engine
Define new partitions
Drop old partitions
Copy data between partitions
Internal NDB triggers between partitions

Most of those functions are already existing so it's more a matter of
connecting things together.