Use opaque colors

[chriadam]

Alpha blending is expensive. Reducing alpha blending by using opaque colors reduces GPU work, and thus swap time.

[DanielMcInnes]

tabs look wonky

[chriadam]

The code which forms part of the output needs tabs, whereas the python code needs spaces. Hence the discrepancy. What is in the PR is correct, I believe.

[DanielMcInnes]

lgtm

[chriadam]

Putting this on hold for now - asked Serj instead if he could just provide opaque colours for all elements. Hopefully he agrees. If not, we can go down this PR path (and maybe provide a Theme.blendColors(elementColor, surfaceColor) mixer function, which calculates the blending for us, rather than manually providing opaque theme colour values).

[chriadam]

Serj provided some opaque colours, but they didn't match the existing colour scheme (it might be intentional or might be a mistake) and a variety of colours were missing, unfortunately. I've added a set of colours which match the previous design, and covers all of the colours we use in our code. I have asked Serj whether these colours need any adjustments.

[MikeTrahearn-Qinetic]

The ability to define opaque colors is dependent on how well defined the colors are in the Figma Design System.
Where there are a small number of common colors set on top of a fairly common set of background colors, it is possible to define sets of pre-multiplied alpha colours - one for each Dark and Light mode. Having gone through this exact scenario on a previous project, this is less than trivial, unless you build it in to the Design System from the beginning.