Add a delay to Alt Shortcuts with custom titlebar

[MarkusAmshove]

I'm using the preview feature for custom titlebars from the June update and I really love the look and feel of it, good job!

One letdown I found was that I can't use any keybindings that conflict with the mnemonic of a menu in the titlebar.

For example:

alt+f used to forward one word within my terminal, but now it instantly opens the File menu
alt+d used to toggle a task in todo+ as completed, but now opens the Debug menu

I'm not sure what the workaround could look like, but I could think about an option which would let me have to hold down alt for 1-2 seconds to access the menus :-)

[MarkusAmshove]

Oops, dupe of #53654