feat: allow more hotkeys to launch cerebro

[gl-web]

Be able to select keys as F9, F7, F5, F8 for launch cerebro ...

[KELiON]

Sounds reasonable, I'll implement it.

Currently only shortcuts with modifier keys (cmd, ctrl, alt, shift) are allowed. You can edit config file to set F1-F24 as a global shortcut

[LuckyLukert]

It would be also nice to have just cmd as hotkey i.e. if you press cmd and nothing else and then release cmd, the action should be triggered.

(sorry, if this already works, I can't test it because of compilation fails on ArchLinux)

[jessebot]

macOS Ventura (13.0)

On macOS, when I was using Alfred, I could use a double tap of the command key as a shortcut to launch Alfred. Setting hotkey: Command+Command, in my config.json doesn't seem to work though. Not sure if this should go in this issue, or if I should open up another, but #100 doesn't apply to me, as I can map Command+Space, and other combinations fine.