Exception request: High contrast frames and separators

[Akseli Lahtinen]

Hi!

I have made an accessibility feature that allows to set high-contrast mode for 
any outlines and frames Breeze style has.

Here is the original merge request:
https://invent.kde.org/plasma/breeze/-/merge_requests/393

Do note that it's been split to three separate merge requests!
However, the above linked MR has still all the relevant info.

The feature exception request is for both style and window deco.
For style, it adds the checkbox toggle that sets the frame either
default color or high contrast color.

In window deco, we just remove the unnecessary settings,
and only have three settings: Off, Default, High Contrast

I do think this would be good to get in ASAP, since it is an accessibility
feature and will be genuinely helpful for many who need high contrast
colors in their setups.

Best regards and happy new year,
Akseli Lahtinen