Added loading indicators to character select and preview load.

[mavisakalyan]

Describe your changes

• Added a loading indicator to character preview.
• Added a characterLoaded state to AppContext so whenever a new character is selected we can catch that action in any component.
• Triggered the character loading in the AvatarIcon component so you can see that a new avatar is loading and not just wait for it to change.

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

• Go to character select menu and load some previews.
• Select a new character and see the Avatar Icon loading triggered.

Issue ticket number and link

https://github.com/webaverse/app/issues/3541

Screenshots and/or video

https://user-images.githubusercontent.com/55106546/184635079-a78dcf9b-df9c-4224-9c22-7303d92b6f24.mov

Checklist before requesting a review

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

[mavisakalyan]

Fixing an error on chrome. Doing a cross browser check.

[zenkale]

@mavisakalyan Looks fine but this Error while we equip the character from character select panel

https://user-images.githubusercontent.com/111510128/188156642-4e007abc-d2cd-49d3-84c4-a3b43a255d81.mp4

[mavisakalyan]

@zenkale looking into it. Thank you.

[mavisakalyan]

@zenkale All fixed please check.