pgsql: injection_points: Add variant for injection_point_attach()

injection_points: Add variant for injection_point_attach()

This new function is able to take in input more data than the existing
injection_point_attach():
- A library name.
- A function name.
- Some private data.

This gives more flexibility for tests so as these would not need to
reinvent a wrapper for InjectionPointAttach() when attaching a callback
from a library other than "injection_points". injection_point_detach()
can be used with both versions of injection_point_attach().

Author: Rahila Syed <rahilasyed(dot)90(at)gmail(dot)com>
Reviewed-by: Mihail Nikalayeu <mihailnikalayeu(at)gmail(dot)com>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Discussion: https://postgr.es/m/CAH2L28sOG2b_TKkZU51dy+pWJtny1mqDmeFiFoUASGa0X0iiKQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/16a2f706951edc1b284a66902c9e582217d37d31

Modified Files
--------------
.../injection_points/expected/injection_points.out | 35 +++++++++++++++++-
.../injection_points/injection_points--1.0.sql | 12 +++++++
.../modules/injection_points/injection_points.c | 41 ++++++++++++++++++++++
.../injection_points/sql/injection_points.sql | 11 +++++-
4 files changed, 97 insertions(+), 2 deletions(-)