Move Multi-HAL 2.0 to the common directory

Sensors Multi-HAL 2.0 will soon have a shared implementation for both
Sensors HAL 2.0 and 2.1 and moving the files to the common directory
first will minimize the diff in upcoming CLs.

Bug: 149758467
Test: compile
Change-Id: I15f84a7aaa302d83d4f4b1ffe357f515e36d6382