Add resource usage metrics in Soong metrics.proto.

We would like to collect the resource usage of processes such as
kati, soong_build and ninja on the resource usage such as memory
and context switching. This changelist contains the defined fields
in the protobuf file of the resource information to be collected
from interested processes.

Bug: b/169453825
Test: N/A
Change-Id: I4b3cbbc3e7b78900875c10d34d574425f8b11730