[RootCanal] Add support for LinkPolicy and RoleChange in RootCanal

Needed for HID PTS tests. We just fake the link policy and our current
role by tracking them locally, rather than using LMP to coordinate with
the peer. This can be changed at a future date if a test depends on this
working.

Bug: 239986609
Test: HID PTS tests
Tag: #feature
Ignore-AOSP-First: Cherry-picked from AOSP
Merged-In: I3b2b97a200b0279251fc68e37e23b8d3cfb8bdeb
Change-Id: I3b2b97a200b0279251fc68e37e23b8d3cfb8bdeb