Add a default color code option for all applications that don't have a specified color code or are not set to be ignored

[ghost]

I noticed the apps that we don't set to use a specific color code for notifications, are grabbing their own color code after their first notification. It would be good to add an option to automatically set a specified color code for all first-time-notifications grabbed by HoleyLight, until we chose to ignore them by setting the color to black or setting our specified color code for these apps manually.

For example: I got my first Gmail notification after installing HoleyLight, and by default the notification light was a light red color.

We can create an option to set a preferred color as default for any new or not already set apps, and use that color code until we manually set the app to use a specified color or just set to black for ignore. In my use case I want 2-3 apps to have a specific color that I already setup and any new/unspecified app notifications to have a color code blue.

That way we can have our already set color codes for our favorite apps, and have a preferred specified color code for all other apps, new or unspecified.