pgsql: Honor run_as_owner option in tablesync worker.

Honor run_as_owner option in tablesync worker.

Commit 482675987 introduced "run_as_owner" subscription option so that
subscription runs with either the permissions of the subscription
owner or the permission of the table owner. However, tablesync workers
did not use this option for the initial data copy.

With this change, tablesync workers run with appropriate permissions
based on "run_as_owner" option.

Ajin Cherian, with changes and regression tests added by me.

Reported-By: Amit Kapila
Author: Ajin Cherian, Masahiko Sawada
Reviewed-by: Ajin Cherian, Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1L=qzRHPEn+qeMoKQGFBzqGoLBzt_ov0A89iFFiut+ppA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a83edeaf684a70da02fa2bce8b7e3aefa3f906f5

Modified Files
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src/backend/replication/logical/tablesync.c | 64 ++++++++++++++---------
src/test/subscription/t/033_run_as_table_owner.pl | 38 +++++++++++++-
2 files changed, 75 insertions(+), 27 deletions(-)