use position and data from chroma unit when treeType = DUAL_TYPE_CHROMA to derive context

implements:
- splitting tiles into bricks
- raster-scan tiles
- uniform and non-uniform splits
- all tiles/bricks in one slice
- each brick one slice
- PPS syntax

missing:
- rectangular tiles
- slice header syntax

further todo:
- rework slice mode 2 to use multiple tiles for byte size matching
- lots of renaming (tile->brick)

  - Fix bugs in N0280 - Transform skip residual coding.

Merge branch 'N0280-ResidualCodingTransformSkip' of https://vcgit.hhi.fraunhofer.de/nguyen/VVCSoftware_VTM into N0280-ResidualCodingTransformSkip

- Harmonize coefficient group sizes of chroma TBs to those used in luma TBs
- For 2x4/4x2 chroma TBs, retain 2x2 CG size.

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

- all elements of SPSNext are moved into SPS
- syntax elements of SPS are sorted according to draft (as far as possible)
- comments were added where software and draft diverge

Use a single array with elements that comprise scan x position, y
position, and index into block instead of separate arrays.

Simplify array initialization code

There is a conflict with JVET_M0427_INLOOP_RESHAPER that is triggering a debug assertion that checks that the width is not 1.

Two changes are included: (1) disable fractional MVD for UHD sequences (M0312 & M0255) (2) encoder optimization for MMVD