CHROMIUM: Merge BlueZ upstream

This patch merges the latest 5.28+ patches from BlueZ upstream, pulling
the most recent GATT server code that we upstreamed as well several new
unit test additions to unit/test-gatt and bug fixes.

Conflicts:
  Conflict in Makefile.tools, due to the upstream patch
  "tools/btmgmt: Add initial readline support". This conflicted with
  our local patch that moved btmgmt out of experimental.

BUG=none
TEST=none

Change-Id: Idb29691b419a8923a86c4334b0876c012364a24b