[NOMERGE] First cut some tests for the kernel

[roscopeco]

Don't merge this, it's slop. Just here as a starting point for when we do want to start doing this...

[github-actions]

Overall LCOV of commit a8f67a1 during compile_and_test #535

Summary coverage rate:
  lines......: 74.7% (9172 of 12283 lines)
  functions..: 76.9% (980 of 1274 functions)
  branches...: no data found

Files changed coverage rate: n/a

[github-actions]

Kernel LCOV of commit a8f67a1 during compile_and_test #535

Summary coverage rate:
  lines......: 83.0% (7212 of 8693 lines)
  functions..: 79.6% (807 of 1014 functions)
  branches...: no data found

Files changed coverage rate: n/a

[github-actions]

Userspace LCOV of commit a8f67a1 during compile_and_test #535

Summary coverage rate:
  lines......: 54.6% (1968 of 3602 lines)
  functions..: 66.5% (173 of 260 functions)
  branches...: no data found

Files changed coverage rate: n/a