ultrahdr: update jpegencoderhelper to accept uncompressed struct fields

With this change we can now pass luma/chroma ptrs and stride information
to jpegencoderhelper class during compression. This by passes
intermediate copy whenever possible

Also updated fuzzer to incorporate 420 stride support

updated jpegr unit tests for more combinations of gamuts and unusual strides

Bug: 294218453
Test: ./ultrahdr_unit_test
Test: ./ultrahdr_enc_fuzzer

Change-Id: Ic50dd34b0c680618e73e0cb27f554b9bf8272e8f