Symlink current prebuilt folder to android root

The Android are now based on Trunk Stable world and Pixel prebuilts CLs
also needs to reply with this which controlled by the flag which results:
- the flag value might be different on each branches
- the flag value are mostly different on each release configuration
- for local builds, ENGs' needs to figure out the correct location
  of current prebuilts by checking through entire prebuilt textproto
  files

To alleviate this problem, create an symlink file under android root
indicates current prebuilt path after invoke the android lunch cmd.

Bug: 364831620
Flag: EXEMPT export current prebuilt path
Change-Id: If91dc0684afdd97eeb7acb22b966705f3a79b896
Signed-off-by: Robin Peng <[email protected]>
5 files changed