VVC follows the concept that parsing of SEIs shall be independent of parameter sets

JVET-S0185_PROPOSAL1: SEI picture timing cleanup, put syntax element pt_cpb_removal_delay_minus1[] first, followed by similar information for sub-layers, followed by pt_dpb_output_delay.

Includes:
- added flag
- minor updates for variable names
- update for trace strings according to JVET-R2001-vA

- fixes other style issues as well