DiagnoseMe: Enforce Servo MAC format and check uninitialized state

Enforce 88:54:1F OUI prefix validation for Servo V4.1 MAC address in
both backend and GUI. Disable Functional Testing card if MAC or
Serial is invalid, and fail console tests if device reports an
uninitialized MAC.

BUG=b:538099956
TEST=Verified unit tests and MAC validation logic

Change-Id: I580b2ff2b589c78165bff08aebb1bc034c167f1b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/hwtools/diagnoseme/+/8158511
Reviewed-by: Michał Headcrab Barnaś <barnas@google.com>
Tested-by: Łukasz Hajec <hajec@google.com>
Reviewed-by: 488603086791@cloudbuild.gserviceaccount.com <488603086791@cloudbuild.gserviceaccount.com>
Commit-Queue: Łukasz Hajec <hajec@google.com>
Commit-Queue: Michał Headcrab Barnaś <barnas@google.com>