Add system/manifest.xml on device

Similar to vendor/manifest.xml on device, this file lists
all HALs defined in the framework (and hence go
to the system image). IServiceManager / IMemory /
etc. getService should consult this file (via VINTF
object under /system/libvintf) to return the HAL in the correct
transport mode.

Bug: 34772739 Create system/manifest.xml
Bug: 35219444 Need interface + instance entry

Test: compiles and manually confirm that system/manifest.xml exist.
Change-Id: I5b3c79b068841e47062cbab6f72d70555801a21d