macOS: Location of OMERO.insight.cfg outside the application to avoid SystemPolicyAppBundles restrictions

[TK5-Tim]

Follow up to #363

In the Pull request #365 the possibility got added to point to a container xml outside the Omero.insight app to avoid the SystemPolicyAppBundles restrictions by Apple (which are currently not enforced because the Omero.insight App is not signed).

The change is very welcome but the problem is that by having to change the link to the container.xml inside the OMEO.insight.cfg File the problem is just moved to a different file.

Is it possible to move that file outside the app as well? The most common way to have config Files for MacOS Applications is storing them in a dedicated folder in the /Library/Application Support/ directory.

[TK5-Tim]

As an addition to the above Issue I would like to refer to the official Apple Developer documentation: https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html#//apple_ref/doc/uid/TP40010672-CH2-SW1