[SDK-607] Add selfie element

[rYuuk]

SDK-607

Description

• Added selfie element
• Clean up elements prefab and scripts

How to Test

• Put prefab in empty scene and also it will require login anonymously

Checklist

• Tests written or updated for the changes.
• Documentation is updated.
• Changelog is updated.

[HarrisonHough]

Overall looks good but some suggestions and discussion points in the comments

[HarrisonHough]

Actually not relevant to this PR, something I kinda missed in Max's PR. But perhaps we shouldn't force them to start the camera on awake (this InitializeCamera function) is automatically called on awake, starrting the camera is also kinda a hidden "side effect" of initializing. I also wonder if it the automatic GetCamDeveice() on start might be annoying for some as it basically requests access regardless of whether the element is actually used? 🤔 Maybe I'm just overthinking this part though.

[MaxAndreassenRPM]

I could see the positives for moving out the StartCamera() method to be invoked outside of awake (maybe in a from the editor itself in the element prefab), but then you'd maybe want the whole initialize method to not be on awake right?

Although since this is so easy to change between, maybe it's one of those ones where it's a case of us getting it out there and seeing what partners say. If we get reports that it is annoying then it's easy for us to change it and to respond to feedback.

[HarrisonHough]

I see what you mean about the body type thing for avatar manager, kinda annoying we need to add to the function params. But I do think it's still better then having the multiple places to set body type. Maybe in future there might be a way to improve it even further somehow.

I mention one small thing in the comments but it's not specific to the changes in this PR and is kinda minor.

But overall great work ! And thanks for making the changes 🙏

[HarrisonHough]

Looks good. Cool stuff