"Alter Column Type" compatibility checks

[tabdulradi]

There is basic validation defined here https://github.com/cassandra-scala/troy/pull/79/commits/0a129ae3e482e85d12e9dcff82427553dfab7933

This needs to cover all cases.

[tabdulradi]

The following datatype changes are not supported:

Changing the type of a clustering column Changing the type of a column on which an index is defined

https://docs.datastax.com/en/cql/3.1/cql/cql_reference/alter_table_r.html#reference_ds_xqq_hpc_xj__changing-the-type-of-a-column