Add support for appsettings.json file in `%PROGRAMDATA%` with appropriate permissions.

[JM-A21]

Currently the application only loads settings from default .NET locations. Add support for settings files in %PROGRAMDATA% on Windows.

[JM-A21]

Completed in commit 9f5902b.

[JM-A21]

Additional testing of release 39a1d03 has found that the %PROGRAMDATA% folder created for appsettings.json is still not using the proper permissions, requiring administrative rights to modify the settings file. Reopening. Apparently the sandbox test environment didn't use the same permissions as a live system.