Bug 430716

SUMMARY
Add the ability to create custom hotkeys in a similar manner as the "Run Command" on the Android App, creating buttons that may be clicked on the phone app to execute a sequence of user-specified key strokes such as `Ctrl+L`, Ctrl+N`, or `Mod4+0`. 

Include the modifiers: `Ctrl`, `Alt`, `Shift`, and the "windows mod key": `Mod4`. Allow for multiple modifiers per sequence: `Mod4+Ctrl+Shift+Alt+1`

Could also add a means of typing in a key sequence in the phone app that does not currently have a button by adding a textbox and send button, and then passing the textbox contents to be typed on the desktop. This would also allow for using the phone's clipboard by the user pasting in the  contents in the textbox of the phone app.

STEPS TO REPRODUCE
[How I see the interface would function]
1. Pair phone and desktop
2. Click "Remote Input" on the phone app
3. Click on an icon next to the keyboard icon (a new added icon to show the possible hotkey commands or key sequences)
4. Select a hotkey to send remotely to be executed on the desktop computer
5. Desktop computer executes the hotkey doing whatever it does within the active desktop application.

OBSERVED RESULT
N/A

EXPECTED RESULT
The hotkey would activate in the active application just as it would if the hotkey was entered by the keyboard locally on the desktop.

SOFTWARE/OS VERSIONS
Windows: N/A
macOS: N/A
Linux/KDE Plasma: Linux 5.9.14.arch1-1 (Linux hardened 5.9.16.a-1) 
(available in About System)
KDE Plasma Version: N/A
KDE Frameworks Version: N/A 
Qt Version: N/A
Current kdeconnect version: 20.12.0-2

ADDITIONAL INFORMATION
None