[FR] Change Extension Options Panel icon so it's different from the Unified Extensions icon

[garywill]

Is your feature request related to a problem? Please describe.
Extension Options Panel button icon is the same as Firefox's Extensions button icon. Two same icons in toolbar makes users confused

Describe the solution you'd like
Make Extension Options Panel in different color

Describe alternatives you've considered
Or give Extension Options Panel a new icon

Additional context
We could simply use CSS fill to change the color of Extension Options Panel button icon

[aminomancer]

You can already do that with CSS:

#eom-button {
  fill: red !important;
}

This is too opinionated of a change to put in the script, and not consistent with the theme's norm of white icons (using blue icons only for some "active" toolbar buttons). Plus, some users hide the unified extensions panel so don't have an issue like this and would be annoyed by the extension options panel button randomly deviating from the normal color scheme.

Changing the icon would be worth considering, but it's a lot of work and pretty low priority, something users can handle in their custom CSS. I'll leave this ticket open in case someone wants to submit a PR, but otherwise I probably won't work on this anytime soon.