Since `preloaded_nanoapps.json` has different configurations for
`factory` products and `non-factory` products, `soong_namespace {}`
needs to be added to the converted Android.bp file to avoid misuse.
Additionally, due to ag/27170565, ag/27170566, a common inheritance
layer has been added to all `non-factory` products. Therefore, setting
different `PRODUCT_SOONG_NAMESPACES` in the corresponding
`<DEVICE>_generic.mk` and `factory_<DEVICE>.mk` files will allow
factory products and non-factory products to use different
preloaded_nanoapps.json.
Bug: 338332183
Test: 1. lunch <product_name>-trunk_staging-userdebug && \
m -j preloaded_nanoapps.json
2. Check ./out/target/product/<device_name>/.../preloaded_nanoapps.json
It should be the <device_name> version.
3. lunch factory_<device_name>-trunk_staging-userdebug && \
m -j preloaded_nanoapps.json
4. Check ./out/target/product/<device_name>/.../preloaded_nanoapps.json
It should be the factory version.
Change-Id: I97798f0e7876ceb016a31f7da74508fe5a701915