[Material] Add ability to swap color palettes

[kazo0]

We should be exposing some sort of way to "switch" color palettes at runtime. Example: a user could be presented with several options for the main color of the app theme

In doing so, we'd need a way to re-initialize the MaterialTheme with the chosen color as an override for something like PrimaryColor.

Not sure how smooth this process would be at runtime, we may need to force a refresh of all ThemeResources by doing something like toggling the ApplicationTheme

[Xiaoy312]

@kazo0 would the proper implementation of lightweight styling enable us to achieve this?
CC @agneszitte

[kazo0]

We could do it that way, I was hoping we could be able to replace the current color overrides with a new set of base colors.

Unfortunately overriding things like PrimaryColor locally doesn't update lightweight styling brushes that alias other brushes based on that resource. So you need to reinitialize all of the resources