Floss: Hcidoc: Add external controller signal

Some users plug an external controller, if the stack somehow use that,
it is likely to fail in various situation as it wasn't tested.

This adds a signal to detect if the chosen controller is an external
controller by checking if the local name and manufacture are in the
known list and also tracking the new index event.

Bug: 325403872
Test: m -j
Test: Using report 91563648247, verify every read local name and the new
index are reported.
Tag: #floss
Flag: EXEMPT, Floss only change

Change-Id: Ia25c4f8deaaa20d4529d412938c3cc1fdcf915c0