Surface ACL disconnect reasons from native to Java

HCI disconnect commands and events have an accompanying "reason"
parameter comprising of a HCI error code. This can be useful in both
debugging and re-connection logic at the Java level.

This CL grabs the HCI codes from native and passes it up to Java via an
extra parameter to existing ACL connection callbacks.

Tag: #feature
Bug: 177668957
Test: atest BluetoothInstrumentationTests

Change-Id: Ic729140b8ffb1273a9ca53cdfd39c9f5d71e1522