Remove Ubuntu 16.04 build configuration

See merge request jvet/VVCSoftware_VTM!2076

Removes out of maintenance OS release and thus old gcc. Runner will be replaced by Ubuntu 20.04.

JVET-V0054: Slice based Rice parameter selection for transform skip residual coding

See merge request !2072

fix #1485: add conformance check for LMCS

See merge request !2071

Change default for ConformanceWindowMode to "1" (automatic padding)

See merge request !2075

Move check for source image dimensions behind padding to allow ConformanceWindowMode=2 to be used

See merge request !2074

JVET-V0106: RRC Rice extension

See merge request !2066

JVET-V0131: Fixing the forward transform matrices for high bit depth coding

See merge request !2073

Change cfg/hbd/12-bit.cfg to set extended_precision_processing_flag equal to 1

See merge request !2070

JVET-V0047: CE3.1 method for the high precision computation of transform scaling

See merge request jvet/VVCSoftware_VTM!2069

JVET-V0078: QP control for very smooth blocks

See merge request !2065

Rename loop filter appropriately to deblocking filter

See merge request !2063

JVET-V0095: Using true original samples for SAO and ALF optimization when MCTF is applied

See merge request jvet/VVCSoftware_VTM!2060

Clean up conformance window code

See merge request !2062

JVET-V0066: Encoder improvements to palette coding for high bit depth

See merge request !2061

- remove deprecated parameters
- variable renaming according to style guide

JVET-V0056: Changes to MCTF

See merge request !2059

Fix variable naming

See merge request !2053

Remove macros from U meeting cycle

See merge request !2058