HPCC-8765 Plugin cmake macros to clean up optional plugins

Added 2 new macros LOG_PLUGIN and ADD_PLUGIN. These are used to add
and log the addition of optional plugins to the platform.

Implemented the usage of these for the current optional plugins in
master.

Signed-off-by: Philip Schwartz <philip.schwartz@lexisnexis.com>
HPCC-8765 Plugin cmake macros to clean up optional plugins

Add options to suppress building of plugins even if the dependencies are
available.

Add option to make missing dependencies fatal.

Fix typo.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4122 from richardkchapman/HPCC-8765-optional-deps-non-fatal

Hpcc 8765 optional deps non fatal

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>