Add DeviceProduct product varible to Soong

For some modules, it is necessary to access the product name from
Soong. In particular, the use case we have identified is that the
product name needs to be appended to the artifact name in the dist
copy.

Bug: 224561567
Test: Unit Tests and build relevant target/modules
Change-Id: Iaa0bfee8ef0d1201d8af02f7fc9e6ef081175da7