pgsql: Allow event trigger table_rewrite for ALTER MATERIALIZED VIEW

Allow event trigger table_rewrite for ALTER MATERIALIZED VIEW

This event can happen when using SET ACCESS METHOD, as the data files of
the materialized need a full refresh but this command tag was not
updated to reflect that.  The documentation is updated to track this
behavior.

Author: Onder Kalaci
Discussion: https://postgr.es/m/CACawEhXwHN3X34FiwoYG8vXR-oyUdrp7qcfRWSzS+NPahS5gSw@mail.gmail.com
Backpatch-through: 15

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/522ae011fa010a74cd74ef13036df5138751eee2

Modified Files
--------------
doc/src/sgml/event-trigger.sgml             | 2 +-
src/include/tcop/cmdtaglist.h               | 2 +-
src/test/regress/expected/event_trigger.out | 5 +++++
src/test/regress/sql/event_trigger.sql      | 5 +++++
4 files changed, 12 insertions(+), 2 deletions(-)