[Request] Show Serial Port Usage in Web UI

[schlimmchen]

Is your feature request related to a problem? Please describe.

No response

Describe the solution you'd like

The SerialPortManager knows well which hardware serial ports are allocated to which user. This info is currently only printed once when a serial port is claimed. It would be beneficial to show the serial port reservations (and available serial ports) in the Web UI in Info -> System (add a new card).

Describe alternatives you've considered

No response

Additional context

I had this idea for a while now, but #1344 reminded me that it would indeed be beneficial to have.