MULE-7367: rewrote launcher module classloader tests to run as unit tests
This change removes the need to use maven shitty plugin, and eliminates a cyclic dependency on requiring artifacts to
be installed int he local repo before being testable.

(cherry picked from commit 765f21f33ec1537878bc8596959237b91dab9703)
MULE-7367: embeded source files along with classes in test jars for classloading tests

(cherry picked from commit 560140337dadf822534634e24b1f833ebbfed52e)