Normalize building generic system image with treble-common.mk

Move the common part from make file of generic AOSP system images into
treble_common.mk, and update the content of common part.

The common part inclueds:

- HAL interfaces
- VNDK libs
- VNDK-SP libs
- Some other modules supporting HAL interfaces
- Some Treble default configuations

Bug: 37927875
Test: boot to home screen with the generic system image
Change-Id: I4202454d57970cef713f7d6437191094df0009e9
Merged-In: I4202454d57970cef713f7d6437191094df0009e9