Adding support for a custom target dir while building, fixing a few issues where the SITE.ipc folder/file was not created for a fresh build

Some functions added to lptc driver to expose diagnostics registers.

lptc specific diagnostics and slot-specific registers brought out in /sys/kernel/gpstime/lptc

some functions that belong to ligoPcieTiming_core.c were moved there from ligoPcieTiming.c

 * simple process management when a test needs multiple processes
 * temp directory management (and cleanup)
 * scriptable
 * less verbose than bash

GDS/AWGTPMAN: missing header files included in src/gds/awgtpman/dtt.  Also gmutex files added to src/gds/base.  These are used by NDS and are separate from awgtpman. Now builds in a pristine container with only mk-build-deps isntalled.

systemd_generator: moved to src/python/cds_frontend.  Will make it into a more generic front end control library.

Sphinx is a documentation generator using reStructuredText:

https://www.sphinx-doc.org/en/master/index.html
https://www.sphinx-doc.org/en/master/usage/restructuredtext/index.html

This builds out the initial skeleton of the documentation.  Changes
can be tested by running make in the documentation tree:

 $ cd doc2
 $ make html

The generated pages are available at

 doc2/_build/html/index.html

This also include gitlab CI to build the documentation at publish it
at the gitlab documentation pages:

 https://cds.docs.ligo.org/advligorts/

added some unit tests for checkdaqconfig.py.  Now accepts hardcoded paths in master template, but will look in expected paths if the paths in the file are dummies (template variables for example).

TP_MAX_NODE increased to 256, which is perhaps the only change needed to awgtpman for increase od dcuid.

TP_MAX_NODE increased to 256, which is perhaps the only change needed to awgtpman for increase od dcuid.