Add german desktop terminal layout

[a-st]

Adds german desktop terminal layout (based on #230)

[Anachron]

Hey, how is it going with this PR? This adds very useful keys that I need to be able to use maliit as my virtual keyboard.

In fact, this is exactly what I've been looking for.

[a-st]

@Anachron I'm currently struggling to get the ctrl key working as intended, but other than that it works perfectly fine. I'm currently thinking about removing the ctrl for now and adding it with a different PR once I figured out how to do that.

[Anachron]

@a-st so the ctrl key currently does nothing? Would you be interested in an alt key?

I am hoping we can get this keyboard to something that is actually useful as a real keyboard for daily working.

I have no knowledge in c++, but maybe I could help building/testing it on real hardware.

[a-st]

@Anachron I have no knowledge in c or c++, either. Nor do I know any QT or QML development. Any help is highly appreciated.

Getting something similar to the Windows 11 on-screen keyboard would be nice

[Anachron]

I was checking the modifications briefly.

You've added event_key = Qt::Key_Control; as per https://doc.qt.io/qt-6/qt.html#Key-enum
But I am not sure if the label strg as per https://github.com/maliit/keyboard/pull/236/files#diff-edad59b3608edd8d79413d4da414538684b4860220bd908ac9078f9a61d0c25aR94 will cause it to not recognize it anymore.

Checking https://github.com/maliit/keyboard/blob/master/plugins/de/qml/Keyboard_de.qml#L88-L94 it never renames these keys, this is across all locales (at least those I checked, de, es and fi).

Edit: Guess what I am trying to say is: Lets keep their names at ctrl and see if that works. It should work with a different name though, as the action property is being matched (like https://github.com/maliit/keyboard/blob/master/qml/keys/ShiftKey.qml#L26) in here: https://github.com/maliit/keyboard/blob/master/src/lib/logic/eventhandler.cpp#L90.

Edit2: I don't think that could be an issue. Label is not matched. No idea what the issue would be. I will see if I can get this PR to run on my setup and will report back if it works here...

[a-st]

Maybe I wasn't clear, as far as I can tell, the Ctrl command is send but it does not yet behave like a sticky key, e.g. like the Shift key. I tried to make the Ctrl key stay in pressed state until another key is pressed but so far I didn't manage to get it to work

[Anachron]

Ah thanks for the clarification, that is Indeed helpful, I think I saw some differences between shift and control behavior in your PR.

Edit: By skimming over https://github.com/maliit/keyboard/pull/236/files#diff-aa8c36e303e82024c5bfc629f9014bb61314d6463cebdc1eb8965ce80c82d197R48-R55 shouldn't that be something like https://github.com/maliit/keyboard/blob/master/qml/keys/ShiftKey.qml#L33-L67?