This commit brings following changes:
1) Implementation of tap based testing using perl language for different
scenarios that could not be covered under traditional SQL based diff testing,
or require server start/shutdown. At this point of time, tap testing is only
enabled for Postgres 14 & 13, for rest of back branches it will be done at
laster time as there is substantial change in number of columns and their
names.
2) Changes to github action workflows for Postgres 14 & 13 to accomodate the
requirements for tap testing.
3) Similarly, minor changes to Makefile are also done.
4) Testing of supported GUCs using tap tests for different possible
configuration.
5) pg_stat_monitor_reset_errors testing using the tap testcases.
6) Insufficient shared space and buffer overflow testing via tap testcases.
7) Some sql scripts under 'scripts' folder to generate some work load requried
for tap test cases.
8) Everything under 't' folder is specific to perl based test cases. It houses
perl files and folders for some expected files and result folder.
9) 90%+ code coverage for LOC and functions.
10) PG-339 Fix by diego, change in pgsm_errors.c.
8647a52856