Flesh out procstats protobufs to have ALL THE INFO!

This involved re-arranging some of the protobuf structs.
What is there now is kind-of awkward, but I didn't want to go
through and just completely change the whole thing.

Bug: 110957691
Test: atest CtsStatsdHostTestCases:ProcStatsValidationTests
Change-Id: I1d59c15c4d0f3dbdea2cf71307debfcafed7938a