[DRAFT] Add cross compilers for robot firmware building on MacOS

[nycrat]

Description

Look at the stacked PR instead: #3799 #3800 #3802

This PR implements support for the following features:

• Plotjuggler (just fixes the default loopback interface name)
• Physical estop
• Diagnostics controller
• TODO Building motor firmware (adds stm32 cross compiler)
• TODO Building thunderloop (adds new cross compiler from our external software repo)

Testing Done

• Flashed robot software (thunderloop)
• Flashed motor board firmware
• Flashed power board firmware

Resolved Issues

Length Justification and Key Files to Review

Review Checklist

It is the reviewers responsibility to also make sure every item here has been covered

• Function & Class comments: All function definitions (usually in the .h file) should have a javadoc style comment at the start of them. For examples, see the functions defined in thunderbots/software/geom. Similarly, all classes should have an associated Javadoc comment explaining the purpose of the class.
• Remove all commented out code
• Remove extra print statements: for example, those just used for testing
• Resolve all TODO's: All TODO (or similar) statements should either be completed or associated with a github issue