Generate Custom Model - Support for color order and 4-channel nodes

[tbuaas]

Is your feature request related to a problem? Please describe.
Enhance the "Generate Custom Model" feature to support more node types than 3-channel RGB, such as GRB, WRGB, etc.

Describe the solution you'd like
It would be nice to be able to select the types of nodes being used to generate the color pattern for generating custom models. For example, with my new Twinkly String 600 RGB+W lights, the controller cannot be programmed to accept just 3-channel RGB (to my knowledge), so 4-channel nodes have to be supported to enable this neat feature on Twinkly RGB+W lights (among others, no doubt).

Describe alternatives you've considered
I tried using the slower "Nodes - Manual" mode of Generate Custom Models, but it activated 3 channels at a time in 3-channel increments, which is misaligned with 4-channel nodes, and lights up two nodes at once, etc. I hacked up the code in PR #3706 (just a hack), and got it to work. I would like to rewrite these code changes in a more useful way that could be a contribution to the project, and am seeking guidance from a core developer.

Additional context
I was hoping for some guidance with regard to the best way to re-use existing code that references color order and node types. It would be a shame to duplicate the code in more than once place for what feels like could be a core enumeration.