pgsql: Move autogenerated array types out of the way during ALTER ... R

Move autogenerated array types out of the way during ALTER ... RENAME.

Commit 9aa3c782c added code to allow CREATE TABLE/CREATE TYPE to not fail
when the desired type name conflicts with an autogenerated array type, by
dint of renaming the array type out of the way. But I (tgl) overlooked
that the same case arises in ALTER TABLE/TYPE RENAME. Fix that too.
Back-patch to all supported branches.

Report and patch by Vik Fearing, modified a bit by me

Discussion: https://postgr.es/m/0f4ade49-4f0b-a9a3-c120-7589f01d1eb8@2ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/94aced8cd0e229670877fe5c406a98d9a4f1b92a

Modified Files
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src/backend/catalog/pg_type.c | 38 ++++++++++++++++++------
src/test/regress/expected/alter_table.out | 49 +++++++++++++++++++++++++++++++
src/test/regress/sql/alter_table.sql | 20 +++++++++++++
3 files changed, 98 insertions(+), 9 deletions(-)