Update MediaFormatShaper

-- differentiate internal vs exported header files
-- handle when both shaper and app specify QP
-- use defined constant for QP feature parameters instead of literal
-- HEVC values for bits-per-pixel based on experimentation
-- tune upper end of range where we shape (change fewer encodings)

Bug: 183211971
Test: VQ test suite
Change-Id: I6ba5b993878dffdaba12509cdea7a4cecbb819f2