Plugin tests: Specify test functions with wildcards

Example:
    ./qtcreator -test CppTools,"test_cpplocatorfilters_*"

If test data is specified, it will be applied to all matching test
functions.

Change-Id: I579d9aa6ac3d3808ea7e71db3c067d468125569b
Reviewed-by: Daniel Teske <daniel.teske@digia.com>