Add an additional layer of inheritance for `aosp_caiman`, and
`aosp_caiman_fullmte`.
This change adds a common layer of inheritance for non-factory
products (caiman_generic.mk). This makes it easier to configure
factory and non-factory products differently.
Non-factory `caiman` products now inherits from
`device/google/caimito/caiman_generic.mk` which inherit from
`device/google/caimito/device-caiman.mk`.
aconfig flags: Flag: EXEMPT mechanical refactoring
build flags: Flag: EXEMPT mechanical refactoring
Bug: 336452008
Bug: 336707436
Test: lunch aosp_caiman-trunk_staging-userdebug && m
lunch aosp_caiman_fullmte-trunk_staging-userdebug && m
Change-Id: Idc9c0e6862f10e2b2543637804af588b382395d9