Import layouts from Qt VirtualKeyboard

This commit imports the layouts from Qt Virtual Keyboard without any changes, see: https://github.com/qt/qtvirtualkeyboard/tree/588e89db840ba94a10e811c482228a9030ed6fc7/src/layouts

We install the layouts here to /usr/share/plasma/keyboard/layouts (or whatever the cmake install path is). Then, plasma-keyboard sets the QT_VIRTUALKEYBOARD_LAYOUT_PATH environment variable to that path.

When we set this environment variable, it only looks in that folder for layouts (and ignores builtin ones), so we need to import all layouts at once.

This gives us the ability to make changes to vkbd layouts for different locales, and other tweaks we need (ex. remove "hide keyboard" button on mobile).