Audio V4: Implement the shim effect 4.0 -> legacy

All the new files added are a copy of the 2.0 ones, with just the
version 2 that was changed to 4.

Due to the rollback on the retrocompatiblity breakage,
the split of implementation is not strictly needed any more.
This makes the current split in .impl.h and double include
unnecessary complicated.
This will need to be factorized in a future patch.

Bug: 38184704
Test: compile
Change-Id: If412eb55ebf6afc773593547af9395a09b6825c2
Merged-In: If412eb55ebf6afc773593547af9395a09b6825c2
Cherry-picked from master
Signed-off-by: Kevin Rocard <krocard@google.com>