Warning Dialog MI shutdown was Not Clean and Point to Logs

[JackEAllen]

Desired Behaviour

We should open a warning dialog window if shutdown of MI was not clean. the warning dialog should also provide a link pointing to the log files produced during a non-clean shutdown of MI.

Providing user with easy identification of a non-clean shutdown of MI and providing users with easy access to the logs produced during the shutdown will improve user bug reports of such instances

Current Behaviour

Mantid Imaging does not warn of a non-clean shutdown to users on closure.

[JackEAllen]

#2365 Settings Tab for Logging is a pre-requisite for this issue