Add easings plugin

[respectZ]

Description

This plugin allows apply easing to Minecraft: Bedrock animation by manipulating anim_time_update rather than per-keyframe basis. Easing can be only applied to animations with default or empty anim_time_update and known animation length (not infinite or 0).

There are few flaws for this plugin:

• Needs to be reapplied if either duration or loop mode has been changed.
  Because easing require t from 0 to 1, and t = current_time/total_duration. There's no molang for getting animation length. Same case with loop.
• Back and Elastic easings aren't supported
  These easings have out of bound value while Minecraft just clamp it within animation length.
• Blockbench preview seems like not showing bounce easings properly?
  I guess this is because it doesn't support playing backwards? I've tested in-game and works perfectly. (Blockbench version was 5.0.7)

Variable names are prefixed and hashed based on animation name, there's shouldn't be conflict or collision between them.

Preview

preview.mp4

There's also Apply Easings to manage all current animations easing with modal or dialog.