Introducing two new colors:
- ColorTheme::color_dim, for dimmed/disabled primary colors
- SurfaceTheme::opaque_widget, for buttons.
In material design, a button's background color uses the Highest
Container role, which seems incorrect because then buttons wouldn't have
a different color when placed inside of the highest level container.
Rather than remove a container level, I added one more tone using the
neutral variant.
Other changes are just gut feelings to have a slightly richer dark
theme. I feel like material is a little muddy in dark mode.
I started making more changes, and I lost track of what was merge
related and what wasn't, so I committed the merge with what was staged,
but it probably didn't compile.
This is the remaining changes to get things back to a state I'm happy
with, mostly tweaking the constrast behavior.
