hw/bluetooth.default.so -> libbluetooth.so (1/2)

Also rename the build goal for both the library and headers.

Bug: 67853426
Test: run Bluetooth
Merged-In: Iaffeebc1d3f2761e13f6d66d4e855dc342603054
Change-Id: Iaffeebc1d3f2761e13f6d66d4e855dc342603054
(cherry picked from commit 842ff8ed7f5b00d5f6da9d975f37e65c41bb8ebc)