Use rules to create partition compatibility symlinks

Creating the symlinks between partitions (e.g /system/vendor to /vendor)
inside the packaging rules requires duplicating the creation in the
system.img rule as well as in the the target-files.zip rule, which can
cause the target-files.zip rule to fail in soong_zip when the symlink
is removed and recreated by the system.img rule.

Now that our Ninja fork supports symlinks in the build graph, move
the symlink creating to their own rules and add them to the list
of files that the image creation and packaging rules depend on.

Fixes: 161280160
Test: m nothing
Test: treehugger
Change-Id: I0f4d16b57b3052efb12a1f086506f1298c22ec84