Fix wrong physical speed and animations jitter in low fps issues ( Make them "frame rate independent" ). ( 2nd try )

[gonnavis]

Describe your changes

Follow this reverted PR: #3422

• Retain the same fixings and improvements of above PR.
• Fix "no idle animations" regression.
• Fix "jump/doubleJump state to fallLoop state hair jitter" regression.
• Compatible with avatar-spriter.

To compatible with avatar-spriter, we can't depend on player and player.charaterPhysics.velocity ( wich already frame rate indepedent after this PR ).
So need calc avatar.velocity without player.charaterPhysics.velocity.
But I think we can't calc "smooth"/"frame rate independent" velocity from per frame movement/positionDiff.
So I added a isBoundPlayer arg to distinguish these two situations:
For normal mode, avatar.velocity copied from characterPhysics.velocity.
For spriter mode, avatar.velocity calced from fixed 60 fps positionDiff.
( The velocity for spriter can be calced, because of the codes in avatar-spriter are assumed always 60 fps. )

app/avatars/avatars.js

Lines 1511 to 1513 in 82fa161

	if (!isBoundPlayer) {
	this.velocity.copy(this.calcedVelocity);
	}

What are the steps for a QA tester to test this pull request?

• Test in low fps, if the movement speed the same as 60 or higher fps.
• Tset in low fps, if the animations still jitter.
• Test if there are idle animations.
• Test if jump/doubleJump state to fallLoop state hair still jitter.
• Test if avatar-spriter mode ( graphics low setting ) work well.

Issue ticket number and link

#3422 (comment)

Screenshots and/or video

Idle animations and hair no jitter:

huddle.20220815.mp4

Compatible with spriter:

velocity.frame.rate.-.spriter.mp4

Checklist before requesting a review

• I have performed a self-review of my code
• I am not adding any irrelevant code or assets
• I am only including the changes needed to implement the change
• I have playtested and intentionally tried to find error cases but couldn't

[gonnavis]

Close in favor of https://github.com/upstreet-labs/app/pull/26

[gonnavis]

rondoor encountered this issue on webaverse/app, so reopened it.