Binder: Clean up JNI code

Factor out Error handling code and clean up. Use ScopedLocalRef,
fix minor logic issues.

(cherry picked from commit 625e0007)

Bug: 64689630
Test: m
Test: manual test
Merged-In: Icc5a1e38fa66aa79d87d0abb81acef6918ca78f5
Change-Id: Icc5a1e38fa66aa79d87d0abb81acef6918ca78f5