Follow API guidelines in BugreportManager

* Add an executor for callback
* Rename *listener to *callback
* Accept ParcelFileDescriptor.

Not changing the binder interface to accept ParcelFileDescriptor because
there seem to a bug in generated java code for "out"
ParcelFileDescriptors causing compilation errors.

BUG: 111441001
Test: Builds
Change-Id: I9caf91b504eacc3ab6ff23620f1d6ded51caee1a