Add TAP tests for role membership in pg_hba.conf

Add TAP tests for role membership in pg_hba.conf

This commit expands the coverage of pg_hba.conf with checks specific to
role memberships (one "root" role combined with a member and a
non-member).  Coverage is added for the database keywords "samegroup"
and "samerole", where the specified role has to be be a member of the
role with the same name as the requested database, and '+' on the user
entry, where members are allowed.  These tests are plugged in the
authentication test 001_password.pl as of extra connection attempts
combined with resets of pg_hba.conf, making them rather cheap.

Author: Nathan Bossart
Reviewed-by: Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/20221009211348.GB900071@nathanxps13