rusty-gd: compile into libbluetooth

adds init flag entry point, currently prints flags

disable the BT apex since it's not shipped yet (won't be for a while)
and there are a bajillion rust libraries we'd need to add apex
availibility to.

Bug: 171749953
Tag: #gd-refactor
Test: gd/cert/run --rhost SimpleHalTest
Change-Id: I54cffe93d5819ffdc8229aef7be23f260483ab66