floss: add metrics logging for adapter state

Complete the adapter state reporting call by creating a utility helper
to fetch boot_id from the kernel file and introducing metrics event
definition and conversion skeletons.

BUG: 232098615
Tag: #floss
Test: emerge-${BOARD} floss

Change-Id: Ied7a7552401b1c2409ce052bde5b242dac956f38