This is a backport of PR #7469 that did not apply cleanly to 4.2 with a trivial conflict, another commit that touched one of the files but in a completely different region.
Closes#7480
* github.com:scylladb/scylla:
materialized views: add a base table reference if missing
view info: support partial match between base and view for only reading from view.
view info: guard against null dereference of the base info
(cherry picked from commit c74ba1bc36)