Add a file collector to the platform.

The file collector takes in a file path and recursively
classifies and provides the amount of storage provided by
each classification. This information can be surfaced in
Settings or to fulfill storage telemetry calculations.

Bug: 32207207
Test: System server instrumentation tests
Change-Id: Iff03260859cd4bbd11e7d60b1825115aad540d48
3 files changed