JVET-AD0388: add nnfpa_num_output_entries and nnfpa_output_flag syntax elements

See merge request !2627

JVET-AD0057 item 2: disallow the post-filter hint SEI message to be present in both a prefix SEI NALU and a suffix SEI NALU in the same picture unit

See merge request !2632

JVET-AD0057 items 3 and 4: Update VclAssociatedSeiList and PicUnitRepConSeiList

See merge request !2630

JVET-AD0057 item 2: disallow the post-filter hint SEI message to be present in both a prefix SEI NALU and a suffix SEI NALU in the same picture unit

Fix #1604: NNPFC constraints check

See merge request !2628

JVET-AD0057 item 6: multi-picture-input constraint

See merge request !2629

Fix #1603 Overflow in importMergeInfo()

See merge request !2626

JVET-AD0056 Item 13: implementation of nnpfa_target_base_flag

See merge request jvet/VVCSoftware_VTM!2625

JVET-AD0233 Items 1,2,6: Add NNFPC constraints and chroma sample location

See merge request !2620

JVET-AD0056 Item 12: remove redundant constraints on nnpfa_target_id

See merge request jvet/VVCSoftware_VTM!2624

Fix RPL construction

See merge request jvet/VVCSoftware_VTM!2621

JVET-AD0091 items 4-6: add constraints for nnfpc padding

See merge request jvet/VVCSoftware_VTM!2612

Clean up code and properly track number and position of active
reference pictures

Copy active references from other list before inserting inactive
references