Add feature to run single test

[schumade-ifx]

Since this merged PR, ceedling supports to run one single test in a file.
It would be great if the testCommandArgs parser can also parse a "${TEST_NAME}" for example. In that case the configuration could look like:
"ceedlingExplorer.testCommandArgs":[
"test:${TEST_ID} --test_case=${TEST_NAME}",
],