Updates to jpeg encoder helper class

[ram-mohan]

• Add support for more sampling formats
• RGB jpeg encode now defaults to 444 sampling format instead of 420
• For unaligned blocks memset chroma planes to 128 to create black borders
• Add more fail safe checks, diagnostics
• Ensure memory is released during encoding failures

Test: ./ultrahdr_unit_test Test: ./ultrahdr_enc_fuzzer