cdc: disallow stable casts in cdc expressions #90354
Description
root@localhost:26257/defaultdb> create changefeed with schema_change_policy='stop' as select d::timestamptz from hasdates;
{"key":"[806776683378376705]","table":"hasdates","value":"{\"d\": \"2022-10-20T00:00:00Z\"}"}
Stable casts like other stable functions should be disallowed by default in cdc expressions as they depend on session data that isn't available when evaluating.
Jira issue: CRDB-20727
Epic CRDB-17161