pgsql: injection_points: Add basic isolation test

injection_points: Add basic isolation test

This test can act as a template when implementing an isolation test with
injection points, and tracks in a much simpler way some of the behaviors
implied in the existing isolation test "inplace" that has been added in
c35f419d6efb.  Particularly, a detach does not affect a backend wait; a
wait needs to be interrupted by a wakeup.

Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/ZxGTONm_ctQz--io@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a7800cf498a36456bf4bd7a52e3b81cc225c5a65

Modified Files
--------------
src/test/modules/injection_points/Makefile         |  2 +-
.../modules/injection_points/expected/basic.out    | 74 ++++++++++++++++++++++
src/test/modules/injection_points/meson.build      |  1 +
src/test/modules/injection_points/specs/basic.spec | 35 ++++++++++
4 files changed, 111 insertions(+), 1 deletion(-)