added sysinfo and radioinfo

[gullradriel]

That PR is adding sysinfo and radioinfo to usb serial commands.

They are reporting the same informations as 'Performance' and 'Radio Settings' when using the DFU button.

Example output:

sysinfo:

ch> sysinfo
M0 heap: 32400
M0 stack: 395
M0 cpu: 22
M4 heap: 0
M4 stack: 0
M0 cpu: 0
M4 miss: 0
uptime: 12
ch>

radioinfo:

ch> radioinfo
receiver_model.target_frequency: 25435000
receiver_model.baseband_bandwidth: 1750000
receiver_model.sampling_rate: 3072000
receiver_model.modulation: 1
receiver_model.am_configuration: 0
receiver_model.nbfm_configuration: 0
receiver_model.wfm_configuration: 0
transmitter_model.target_frequency: 25435000
transmitter_model.baseband_bandwidth: 1750000
transmitter_model.sampling_rate: 3072000
ch> 

Solve enhancement issue #1768

[htotoo]

LGTM