powermanager: Introduce PowerExt supported boosting

* This patchset allows for custom boost hints
  to be piped to the Pixel version of the
  AIDL power HAL extension.

Signed-off-by: betaxab <betaxab@gmail.com>
Signed-off-by: electimon <electimon@gmail.com>
Change-Id: I6b687a651832481fe32cd6e1a2578236fe0be5b6