New UI: Impossible to set the icon colour for the top-right icons

[SammyIsConfused]

Describe the bug
Even though the Theme Settings includes a "Icon Colour" setting, this setting (and all the others) do not affect the icons in the top-right of the screen. This prevents creation of a "Dark Mode" theme, as dark colours will make these icons hard or impossible to see (since the colour cannot be changed from black).

To Reproduce
Steps to reproduce the behavior:

1. In the new UI as an admin, visit Settings -> UI -> Edit Theme Settings.
2. Set the Primary Colour to very dark and the Icon Colour to very light (e.g #070707 and #FFFFFF) and click Save.
3. Note that the top-right icons are invisible against the black appbar, even though the icon colour should be white.
4. Set all the rest of the colours to very light (#FFFFFF) and click Save again.
5. Note that the top-right icons are still invisible against the black appbar.

Expected behavior
Icon Colour should control these icons.

Screenshots

dark.mode.problem.mp4

Platform:

• OpenEquella Version: 2021.1+
• OS: Agnostic
• Browser: Agnostic