Support updating an Iceberg table's partition scheme

[alexjo2144]

Iceberg supports adding and removing partition columns after a table has been created, we should have ALTER TABLE statements that perform these operations.

#1324

Syntax-wise, the way it looks in Spark is ALTER TABLE ... ADD/DROP PARTITION FIELD ....
We could do ALTER TABLE ... SET PROPERTIES partition = ARRAY[<partition>], the main usability problem I see is that you would have to re-specify any partitions you don't want removed when updating the list.
Alternatively, we could also have an ALTER TABLE ... EXECUTE <add/drop>_partition procedure

[findepi]

This will be implemented as

ALTER TABLE table_name SET PROPERTIES partitioning = ARRAY[...];