Use muted colors for taxon tiles

[grantfitzsimmons]

Replaces the d3 scheme with a custom set of colors that matches the previous behavior

This has been requested a few times by users since our default taxon tiles colors changed.

Fixes #1859

New Appearance

issue-1859 on left, v7.7 on right in advertisement screenshots

Background Information

This is simply an aesthetic change

I tested all of the categorical color schemes out of the box included in d3 but none of them were satisfactory. I think Max chose the right one when it was updated, but the style that users have required

schemeSet2 (current)

Other default options:

schemeAccent

schemePaired

schemePastel2

schemeSet3

schemeTableau10

schemeSet1

schemeCategory10

schemePastel1

schemePastel2

Checklist

• Self-review the PR after opening it to make sure the changes look good
  and self-explanatory (or properly documented)

Testing instructions

1. Configure the home screen to show Taxon Tiles
2. Verify the change appears in light mode
3. Verify the change appears in dark mode
4. Provide feedback on the color scheme in your review

[emenslin]

Looks good! I feel like the color schemes in both light and dark mode blend in a lot better and are less jarring now. I feel like light mode might be a little bright with the white borders, however I am normally in dark mode so that's probably just a me thing.

[pashiav]

It looks great in dark mode! In light mode, I feel that it is hard to see some of the small tiles because of the light colored border and the width of it.

Aesthetically though, the colors look good! It matches the Specify color palette.

[bronwyncombs]

Colors are pleasing and compliment the Specify brand well.

Tiles are visible/distinct in both light and dark mode, although slightly more clear in light mode, IMO.

dark mode:

light mode:

Congrats on a great idea turned successful PR @grantfitzsimmons!