Added syntax element display_elemental_periods_minus1 to the picture
timing SEI message
Check that the frame field information SEI message signals the same
value as the picture timing SEI message

Signalling of CPB timing parameters for sub-layers in DU-based HRD
operations
Remove pt_max_sub_layers_minus1 and use corresponding syntax element in
BP SEI
Make parsing of BP, PT and DUI SEI independent from SPS

 Implementation of the Dependent RAP indication SEI message. Pictures are marked as DRAP pictures using the encoder config parameter DRAPPeriod, which sets DRAP pictures periodically. Conformance checks are performed at the decoder side to verify that the DRAP pictures follow the constraints in the VVC specification.

- tiles are in the VVC spec for 3 meeting cycles now
- cleanup helps with adaptation for tiles to current draft