Revert "Remove Fast Pair system APIs."

This reverts commit 74607dd786b9cbe017b5785833bd8e6d3a8cf4d8.

Reason for revert: Continue development in T+/U

Bug: 227513829
Test: cts test
Ignore-AOSP-First: nearby_not_in_aosp_yet
Change-Id: Ib648ed7163a2e1f11eeed3d0d3469decf64d9d86
CTS-Coverage-Bug: 205591293
10 files changed