Add NotNull Settings / Preferences

[edwardrowe]

Settings would include:

• Bool whether or not to run NotNulLFinder on Launch
• Ignore paths - assets to ignore during NotNullFinder

Could include:

• whether or not to log info about the search
• output string format for errors

This should implement preferences similar to how Console Pro uses prefs.

[edwardrowe]

Additional setting:

• Whether or not to prevent you from playing when there are nulls

Use the new SettingsProvider to implement this. See Mulligan for an example.