Investigate potential crash when unloading dlls that use Qt Quick

While investigating QTBUG-56172, we found that the sample app attached to that issue crashed during shutdown even if qAxLock() was called from within the SimpleQmlApp server's initialization function. This could be an indication that Qt Quick apps may cause crash if it is transiently loaded in a dll which is later unloaded independently of COM and Active Qt.

Aim of task:

• Understand if unloading crash is isolated to Active Qt or if it is a general problem.

Steps to reproduce:

• Compile and register SimpleQmlApp from QTBUG-56172 after adding a call to qAxLock() inside SimpleQmlApp constructor
• Insert SimpleQmlApp control in testcon sample app from ActiveQt with debugger attached
• Close testcon

Expected results

• Clean shutdown

Observed results

• Crash during shutdown