Add FC blackbox integration

[singlag]

Extra function for some FC not have on board storage/tf card and don't want to buy open lager
It will dump the serial port data to file depend on FC setting (by checking the "/blackbox/dump_tty_date '+%Y%m%d-%H%M%S'.log", file should be 0KB before ARM)

• when MSP is enable at betaflight, will stop dump serial port data and remove file
• when serial port set for "blackbox logging", serial data will save at "/blackbox/dump_tty_date '+%Y%m%d-%H%M%S'.log"

enable "Fast serial" and disable some blackbox headers to save logging overhead
example for filter tuning :
blackbox_disable_bat = ON
blackbox_disable_mag = ON
blackbox_disable_alt = ON
blackbox_disable_rssi = ON
blackbox_disable_acc = ON
blackbox_disable_gps = ON

blackbox_disable_pids = ON
blackbox_disable_rc = ON
blackbox_disable_setpoint = OFF
blackbox_disable_gyro = OFF
blackbox_disable_debug = OFF
blackbox_disable_motors = ON

blackbox_sample_rate = 1/4
blackbox_device = SERIAL
serial 1 128 230400 57600 0 230400

example blackbox log by airunit :
https://drive.google.com/file/d/1P9ec8A5KaPk-B-X7xyCkKzkZl2Nvf1eA/view?usp=share_link

[benlumley]

Feels like this should be its own package rather than part of msp osd?

But is this currently the only way because of how msp osd hijacks the msp steam?

[singlag]

Feels like this should be its own package rather than part of msp osd?

But is this currently the only way because of how msp osd hijacks the msp steam?

because msp-osd already do everything about hijacks the msp steam, and if create another package for "blackbox logging", it may conflicts if msp-osd / "blackbox logging" are both running

[bri3d]

I think we should implement this switching functionality at either as a separate package at a higher level using dini (stop the mux service, check the port for data, and swap to blackbox if there's no data, otherwise start it) or by implementing a feature in msp_displayport_mux to pass raw data into a UDP endpoint and writing a logger based on that. This startup script based approach seems super fragile