Convert build system to soong using Android.bp

* Convert top level Android.mk into build templates in build/Android.bp
  and build/fluoride.go
* Initial conversion is done by "androidmk Android.mk > Android.bp"
* Android.bp does not allow source inclusion from external directories
  and therefore they have to be made in to cc_library_static in their
  respective sub-directories and linked using whole_static_libs in the
  modules where they are used
* As Android.bp does not allow multiple modules of the same name,
  same-name mudules for different target are merged into one definition
  with target specific setup
* Generated proto header path has to be changed in osi/src/metrics.cc as
  Android.bp only generate header path relative to the Android.bp file
  instead of top-level directory such as system/bt
* Android.bp does not support resource copying yet and hence conf files
  are left un-touched.
* Android.bp does support conditional module declaration and therefore
  test-vendor libs are left untouched except for unit tests
* The goal of this CL is to direct (almost) translate Android.mk to
  Android.bp first with Android.bp specific optimizations coming later

Bug: 32958753
Test: Code compilation, manual testing by test team

Change-Id: I5249e1f2135c4121205619b1d735ce448feb7499