[RFE] Docker Autotest: New control file example

Because everybody seems to want moe controw!

This one accepts the legacy ``--args=<csv,list,of,subtests>`` but adds two more space-separated options ``i=<csv,list,to,include>`` and ``x=<csv,list,to,exclude>``.  It also introduces a control-specific configuration file ``control.ini``.  Command-line options are combined with options in the control configuration file then the whole lot is written back out into the Autotest ``results`` directory for later reference (including by subtests if needed).

If this looks good, the next step is to extend the ``SubSubtestCaller`` class to read ``<self.job.resultdir> / control.ini`` and **NOT** load any sub-subtest module that's not also listed in the ``subtests`` configuration option.  This is the key to how we avoid needing to raise TestNaError for skipping tests.