pgsql: Propagate ALTER TABLE ... SET STORAGE to indexes

Propagate ALTER TABLE ... SET STORAGE to indexes

When creating a new index, the attstorage setting of the table column
is copied to regular (non-expression) index columns.  But a later
ALTER TABLE ... SET STORAGE is not propagated to indexes, thus
creating an inconsistent and undumpable state.

Discussion: https://www.postgresql.org/message-id/flat/9765d72b-37c0-06f5-e349-2a580aafd989%402ndquadrant.com

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/bf7233ee4a546219b078b5a0afc654ec02958bee

Modified Files
--------------
contrib/test_decoding/expected/toast.out  |  4 +++
contrib/test_decoding/sql/toast.sql       |  5 ++++
src/backend/commands/tablecmds.c          | 47 +++++++++++++++++++++++++++++++
src/test/regress/expected/alter_table.out | 20 +++++++++++++
src/test/regress/expected/vacuum.out      |  4 +--
src/test/regress/sql/alter_table.sql      |  6 ++++
src/test/regress/sql/vacuum.sql           |  4 +--
7 files changed, 86 insertions(+), 4 deletions(-)