Daemon should dekey a radio before closing

[nyaaaaaaatalie]

Describe the bug
When testing something, the daemon had crashed due to an unhandled exception. I had just pressed PTT on the console. After the daemon crashed, the radio continued to transmit.

To Reproduce
Steps to reproduce the behavior:

1. Transmit via console
2. Cause the daemon to exit
3. Verify the attached radio is still transmitting

Expected behavior
Whenever the application exits, an effort should be made to attempt to dekey the connected radio.

Screenshots
n/a

Device Information (please complete the following information):

• OS: Linux aarch64
• RC2 Version git-hash-fd25c9008428317272b563aecd38c991e6ddeea1

Additional context
n/a

[W3AXL]

Unfortunately, if the exception is with the SB9600 communication routine then there will be no way to dekey the radio without re-establishing a connection. In reality, the error handling of the SB9600 routines needs to be much more robust.