[DO NOT MERGE] Add FastPairClient

This works as an API interface for UX to communitcate with backend.

Test: Built band verified flow manually
Bug: 196262706
Change-Id: I018e0f967f50d58772b746618bbf15391072b490
(cherry picked from commit 314456f8aa7a1cb48ee617e5930601009e9bfa6a)
1 file changed
tree: b00780d874b22f2147d1eebd1a2ea295fe9eba40
  1. nearby/