Make it possible to change the accent color globally

[simonwep]

Note

As originally reported by @zenminimalist

Excepts from the conversation in #64:

And lastly, have a setting where the user can globally change the accent color from black to say blue or and hex color. In the dark version, you could limit it to sensible colors, b/c black wouldn't make much sense 🤣
[...]
I'd think about consolidating some icons/settings in the least vertical bar. Accent color isn't something you change on the fly, but generally you do initial. So I'd create a dedicated settings page/icon for all the system-wide, less-frequented settings and nerd-features e.g. language, accent color, number format...Settings that are used frequently can/should have a dedicated button on the left sidebar.

Requires evaluation of what colors may be applicable and additional evaluation of an addition settings screen or deeply nested dropdowns in the navigation.