[msom] Support burnin tests

[scott-brust]

Problem

Factory burn in needs to support MSoM hardware, specifically the GPIO pinout

Solution

Adds MSoM DVT pinmap to GPIO tests.
Basic cellular test: turn on modem, query IMEI/ICCID/Modem firmware
GNSS test: turn on modem, configure for GNSS, poll for a fix for up to 90s. If there is no lock after 90s, the test fails

Steps to Test

Jumper the following pins together on the M2 EVB (based off the silkscreen names):

CTS   <--> RTS
CS    <--> MISO
MOSI  <--> SCK
GPIO0 <--> GPIO1
PWM0  <--> PWM1
PWM2  <--> PWM3
SOM6  <--> SOM7
A0    <--> A1
A2    <--> A3


Jumper wire for these two sets:
EVT HARDWARE:
SOM5 <--> SOM12
A4     <--> SOM11

DVT HARDWARE:
SOM5 <--> SOM12
A4   <--> A7

Remove all of the Ethernet and SD card jumpers

Example App

Run Tinker. To force burnin mode change this line in tinker setup

BurninTest::instance()->setup();  -->  BurninTest::instance()->setup(true);

References

Ask scott for more info on gpio pins

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[technobly]

Do we want to check if it turns off? Maybe add turnModemOff()? It could also not explicitly fail the test with false if it doesn't turn off.

[scott-brust]

Its not required that the modem be off for the test to be considered successful. This is just an attempt to maintain state after the test is complete. If the modem fails to power on for subsequent cell/gnss tests, that is a legitimate failure though.

[technobly]

turnModemOff() ? It could also not explicitly fail the test with false if it doesn't turn off.