Fix staging dir creation for adevice

Adevice does a `ninja -t inputs -i droid` and filters the results
for out/target/product/ to find files in the staging directories.
We were just copying the staging directories without creating ninja
rules before, so that failed. Actually create the ninja rules.

The rules are created in the android_device module instead of the
filesystem so that if you have multiple filesystems, they don't create
conflicting installation rules.

We should provide a way for tools like adevice to query the build system
for installed files, no matter where they are in the out/ dir, and
use that to replace this logic.

This cl produces the following diff in out/target/product compared
to soong-only builds before this change:
https://paste.googleplex.com/4624734193713152

It's mostly empty directories, which I don't think matter for adevice.

Bug: 393464638
Bug: 392957226
Test: `m installclean && m && launch_cvd && adevice update` says the device is up-to-date.
Change-Id: Ifb52aaf5bc3edd2e3900546bf9df73a52d1022c0