Put DEVICE/PRODUCT overlays in different partitions

This change changes auto-generated RROs from DEVICE_PACKAGE_OVERLAYS
to be generated in the vendor partition, as opposed to /product where
they were generated in the past.

Note that PRODUCT_PACKAGE_OVERLAYS continue generating RRO packages
to /product, which means that a single app can be overlayed from
different partitions. These RROs have been given module and package
names based on their location.

Bug: 127758779
Test: verify noop on presubmit targets
Change-Id: I5cee70e28e3969e67b2d83eaf25d9c6e3a11102d