Allow google dialer code to be compiled against M and N SDKs

+ Class SdkSelectionUtils to provides information of the SDK the app is
  build against.
  Specifically, information that change when the TARGET_N_SDK build flag is
  set in the makefile.
  This is not related to the targetSdkVersion value in AndroidManifest.xml.

Bug:26330692
Change-Id: Ie9e7d734964b5da930d33f69650643bfd2c1e178