Asserts that a schema exists or does not exist.
Schemas can be specifed by either their subject name, id or both.
TIMEOUT clause specifies the amount of time to wait for the assertion to succeed before failing.
TIMEOUT clause is not present, then ksqlDB will use the timeout specified by the server
ksql.assert.schema.default.timeout.ms, which is 1000 ms by default.
If the assertion fails, then an error will be returned.