Text styles should be inheritable about bevy

[alice-i-cecile]

I would much prefer other tools for composition: I have been endlessly frustrated by style-inheritance in the past due to how poorly organized and difficult to reason about it is. That said, we need to at least demonstrate patterns to show how to build and compose styles, both for text and other UI elements.

I really like the list of text properties though, and want to have first class primitives (components maybe?) for all of those so users can quickly modify one property independently.