Initial 1.20.6 support (#2616)* 1.20.5 part 1: bump version numbers* 1.20.5 part 2: bulk update revision number* 1.20.5 part 3: initial changes to make it compile* Few minor fixes* Bump paper version* Account for `ItemFlag` naming change* Compile against 1.20.4 for old version support* Bump to 1.20.6* Bump `TODO`s as well* Compact with older versions* Remove profile handling TODO (commit: 4f24205)