Add a setting to enable the using the Accent Color for the titlebar

Summary of the new feature/enhancement

My feature request is the following: Currently, there is this huge tab at the left of window Title:
https://i.imgur.com/NkCGn3f.jpg but the problem here is, that I am using an accent color that overwrites the title bar for every application.

So I wanted to ask if it would be possible to give us a feature, that we can change that the color of the title bar on the left to the other color, or at least a feature that it automatically gets the same color as the accent color.

Thanks for reviewing.

[zadjii-msft]

I'm changing the title to be slightly more specific.

After #929 we stopped using the accent color, and started drawing the entire titlebar ourselves.

#1934 made the appearance of the titlebar better, but still doesn't use the accent color.

We'll need some way of setting the resources at runtime to override the Background property of the TitlebarControl (introduced in #1948).

This is also related to #1625.

[WSLUser]

Any way ColorTool can help with this too? At some point, it may be better to merge Terminal and ColorTool together and use ColorTool for the colors and Terminal settings for applying them based on what's configured in the Settings UI (alternatively the json). I don't think too much rework would be needed here as the functionality would remain but the commands used for executing would be altered. While ColorTool can remain useful on it's own, anybody who can will probably use the Windows Terminal, especially once it reaches v1.

[mdtauk]

Are you able to query the registry to see if that setting is turned on?