L2SS-1487: Install station control into lofar-device-base docker image

Uses environment variables TANGO_STATION_CONTROL and TANGO_SKIP_BUILD to install station control Python package into lofar-device-base docker images. The TANGO_STATION_CONTROL controls if the package is installed during container startup allowing for rapid development setups.

Additionally, this requires the make build system to execute tox with might not be feasible under every circumstance (particularly docker:xxx docker images) for this the TANGO_SKIP_BUILD environment variable can be set. Be sure to have a valid *.whl available in the tangostationcontrol/dist directory prior to executing make in this case.

The Makefile will automatically erase temporary directories it creates but care is needed to ensure tangostationcontrol/dist only contains a single wheel package of Station Control (SC). Otherwise the make context command will copy multiple wheel packages to the temporary directory subsequently having make build lofar-device-base attempt to install multiple versions of the same package which will fail.

Closes L2SS-1487