Control module thread handling issues

[mraduldubey]

Describe the bug We add control module in a pipeline via the PipeLine interface using addControlModule method.

• We start the control module in its own thread like any other module
• But we do not join it in wait_for_all or stop or term
• This might cause undefined behaviour & must be fixed

To Reproduce Steps to reproduce the behavior:

1. Create a pipeline
2. add control module
3. wait for all
4. Repeat 10 times in same process, see the number of threads /behaviour

Expected behavior We should handle the pipeline end for control module gracefully

[mraduldubey]

More comment:

1. We should handle control module thread specially in the following way:
   • Start it separately (in init(), start() & run_all_threaded())
   • DO NOT pause/play it in PipeLine::pause() / PipeLine::play() because we need control module running even when pipeline is paused for it to process commands
   • Handle it separately in PipeLine::stop() & PipeLine::wait_for_all() methods

[mraduldubey]

I am working on this on md/controlModulePipelineFixes Will also do the following:

1. Register health callback extention
2. Add tests for simple control module
3. Fix pipeline related bugs