Add guardrail to block DDL/DCL queries and replace alter_table_enabled guardrail

Sometimes we want to block DDL/DCL queries to stop new schemas being created or roles created. (e.g. when doing live-upgrade)

For DDL guardrail current implementation won't block the query if it's no-op (e.g. CREATE TABLE...IF NOT EXISTS, but table already exists, etc. The guardrail check is added in apply() right after all the existence check)

I don't have preference on either block every DDL query or check whether if it's no-op here. Just we have some users always run CREATE..IF NOT EXISTS.. at startup, which is no-op but will be blocked by this guardrail and failed to start.

4.1 PR: https://github.com/apache/cassandra/pull/3248

trunk PR: https://github.com/apache/cassandra/pull/3275