display entity support (#2469)* `billboard` -> `EntityPivot`* `brightness_*` -> `EntityBrightness`* `EntityPivot` - minor fixes* `glow_color` -> `EntityGlowColor`* `width`/`height` -> `EntityCullingWidth/Height`* `interpolation_delay` > `EntityInterpolationDelay`* `EntityInterpolationDuration`* `shadow_radius` -> `EntityShadowRadius`* `shadow_strength` -> `EntityShadowStrength`* `transformation_scale` -> `EntityScale`* `transformation_translation` > `EntityTranslation`* Better `DisplayEntityData` transformation handling* `view_range` -> `EntityViewRange`* `item_transform` -> `EntityDisplay`* `text_alignment` -> `EntityDisplay`* `text_line_width` -> `EntityLineWidth`* `text` -> `EntityText`* `text_opacity` -> `EntityOpacity`* `EntityDefaultBackground`* `text_is_see_through` -> `EntitySeeThrough`* `text_is_shadowed` -> `EntityTextShadowed`* Cleanup `EntityDisplayEntityData`* Fix `EntityGlowColor` typo* `interpolation_delay` -> `interpolation_start`* `interpolation_duration` meta fix* Properly handle signed->unsigned in `EntityOpacity`* Improve `EntityViewRange` meta* `EntityCullingWidth/Height` > `EntityWidth/Height`* Document what values can be interpolated* Minor `PropertyRegistry` ordering fix* Minor meta fix* `DisplayEntityData` - comment out background color* Meta fixes* `PaperAPITools#getText` (Spigot): `null` -> `""`* Minor meta fixes & code cleanup* `synonyms` and typo fix* Add interpolation language doc* Reference interpolation lang in mechs* Document `opacity` edge-case* Copypasta fix* `EntityLeft/RightRotation`* `left/right_rotation` -> `primary/secondary`* Revert "`left/right_rotation` -> `primary/secondary`"This reverts commit bcaafa57fdaa76252903b56d4ac21ae1d9d1b7ce.* Document `left/right_rotation` (commit: 3bbe017)