Allow multiple tests in each system test python module

[Martyn Gigg]

The full runAnalysisTest script allows multiple tests per module however the debugging runIndividualTest script does not.

Extend the script to take an argument such as

python runIndividualTest DirectInelastic.TestA

which run just run the TestA test in the DirectInelastic module. All tests in the module can be still be run by just giving the module name.

[Martyn Gigg]

(In [11634]) Fixes #3033. Extend the runIndividualTest system test script to take into account multiple tests in a module

[Stuart Campbell]

This ticket has been transferred to github issue ​3880