Add RS485 file handle for mbed crash log redirection

[sebromero]

This PR adds a RS485 file handle for mbed based platforms. This is used to capture crash logs on Mbed-based boards that support RS485 but don't have other serial output options such as the Arduino Opta.
The corresponding header is not included in the umbrella header but needs to be included explicitly when needed.

[sebromero]

The mbed days are counted, but still :-) FYI @manchoz @pennam

[github-actions]

Memory usage change @ 5110146

Board	flash	%	RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A
arduino:mbed_opta:opta	🔺 +416 - +480	+0.02 - +0.02	🔺 +16 - +16	0.0 - 0.0

Click for full report table

Board	examples/RS485CrashLog flash	%	examples/RS485CrashLog RAM for global variables	%	examples/RS485Passthrough flash	%	examples/RS485Passthrough RAM for global variables	%	examples/RS485Receiver flash	%	examples/RS485Receiver RAM for global variables	%	examples/RS485Sender flash	%	examples/RS485Sender RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
arduino:mbed_opta:opta	N/A	N/A	N/A	N/A	416	0.02	16	0.0	480	0.02	16	0.0	416	0.02	16	0.0

Click for full report CSV

Board,examples/RS485CrashLog<br>flash,%,examples/RS485CrashLog<br>RAM for global variables,%,examples/RS485Passthrough<br>flash,%,examples/RS485Passthrough<br>RAM for global variables,%,examples/RS485Receiver<br>flash,%,examples/RS485Receiver<br>RAM for global variables,%,examples/RS485Sender<br>flash,%,examples/RS485Sender<br>RAM for global variables,%
arduino:mbed_portenta:envie_m7,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A
arduino:mbed_opta:opta,N/A,N/A,N/A,N/A,416,0.02,16,0.0,480,0.02,16,0.0,416,0.02,16,0.0

[github-actions]

Memory usage change @ 5ecab3f

Board	flash	%	RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A
arduino:samd:mkr1000	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrfox1200	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrgsm1400	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrnb1500	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrvidor4000	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwan1300	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwan1310	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwifi1010	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrzero	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:mbed_opta:opta	🔺 +416 - +480	+0.02 - +0.02	🔺 +16 - +16	0.0 - 0.0

Click for full report table

Board	examples/RS485CrashLog flash	%	examples/RS485CrashLog RAM for global variables	%	examples/RS485Passthrough flash	%	examples/RS485Passthrough RAM for global variables	%	examples/RS485Receiver flash	%	examples/RS485Receiver RAM for global variables	%	examples/RS485Sender flash	%	examples/RS485Sender RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
arduino:samd:mkr1000	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrfox1200	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrgsm1400	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrnb1500	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrvidor4000	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwan1300	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwan1310	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwifi1010	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrzero	N/A	N/A	N/A	N/A	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:mbed_opta:opta	N/A	N/A	N/A	N/A	416	0.02	16	0.0	480	0.02	16	0.0	416	0.02	16	0.0

Click for full report CSV

Board,examples/RS485CrashLog<br>flash,%,examples/RS485CrashLog<br>RAM for global variables,%,examples/RS485Passthrough<br>flash,%,examples/RS485Passthrough<br>RAM for global variables,%,examples/RS485Receiver<br>flash,%,examples/RS485Receiver<br>RAM for global variables,%,examples/RS485Sender<br>flash,%,examples/RS485Sender<br>RAM for global variables,%
arduino:mbed_portenta:envie_m7,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A
arduino:samd:mkr1000,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrfox1200,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrgsm1400,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrnb1500,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrvidor4000,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwan1300,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwan1310,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwifi1010,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrzero,N/A,N/A,N/A,N/A,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:mbed_opta:opta,N/A,N/A,N/A,N/A,416,0.02,16,0.0,480,0.02,16,0.0,416,0.02,16,0.0