[BasicUI] Integrate ChartThemes in BasicUI themes

[hreichert]

This PR integrates chart themes to the BasicUI.

• Basic UI styling changed to SASS + initial theming support #4137 introduced BasicUI themes
• [UI] Charts Enhancements: Themes, DPI, legend hiding #4291 introduced chart themes

Take a matching ChartTheme for the current BasicUI theme:

• If the dark theme is choosen in BasicUI, render a dark chart.
• If the default theme is choosen in BasicUI, render a bright chart.

As the bright chart theme has the same colors as the previous/current chart, there is no change if someone uses the default BasicUI theme.

BasicUI default:

BasicUI dark:

[kaikreuzer]

Excellent, thanks!