This patch allows a view schema to be frozen. To unfreeze such a
schema, we add an is_view attribute to the schema idl.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
We want the node's schema version to change whenever
table_schema_version of any table changes. The latter is calculated by
hashing mutations so we should also use mutation hash when calculating
schema digest.
We must use canonical_mutation form to allow for changes in the schema
of schema tables. The node which deserializes schema mutations may not
have the same version of the schema tables so we cannot use
frozen_mutation, which is a schema dependent form.
