Feature/compact harness test

### Description
Just a simple test using an external sourced file with utility functions for harness test scripts.
Tested it on one harness test file, accept_fail and it works.
More complex files (cm_forward*) might not work 'out of the box'.

Not that the variable CONTEXTBROKER_TESTENV_SOURCED has been added to testEnv.sh and that now the harness tests source testEnv.sh themselves if necessary.