pgsql: oauth: Classify oauth_client_secret as a password

oauth: Classify oauth_client_secret as a password

Tell UIs to hide the value of oauth_client_secret, like the other
passwords. Due to the previous commit, this does not affect postgres_fdw
and dblink, but add a comment to try to warn others of the hazard in the
future.

Reported-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/20250415191435.55.nmisch%40google.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e974f1c2164bc677d55f98edaf99f80c0b6b89d9

Modified Files
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src/interfaces/libpq/fe-connect.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)