init: split property context into platform & non-platform components

Bug: 33746484
Test: Successfully boot with original service and property contexts.
Test: Successfully boot with split serivce and property contexts.
Test: 'getprop -Z'
Change-Id: Ib9c087115040c1609aa64a3ed66d4e67e937e33d
Signed-off-by: Sandeep Patil <sspatil@google.com>