Make single rust target

Move hal, hci, link, main to stack/
Move hci::custom_types to packet/, since main target already depends on
packet.
facade_proto doesn't need hci/custom_types.

Test: compile on android and chromeos
Bug: 191711152
Tag: #gd-refactor
Change-Id: I8c25c1fcc61bfe8f93d9ee9bbe1f53986797d863