Prepare api directory for udc mainline branch

udc-extended-api directory will be used only in udc mainline branch to
hide @FlaggedApi annotated api which is not supported in that branch

Copied api directories from udc mainline branch.

Bug: 299411828
Test: TH
Change-Id: I86023b1fb3e5f9b4b787a564303e6d2e60f74467
24 files changed