Rework Loading Screen State

[HexaField]

Summary

🤖 Generated by Copilot at 59ba572

This pull request simplifies and optimizes the loading UI and user avatar logic by using a new userReady property in the EngineState. It removes unused code and imports from several files, and updates the LoadingUISystem.tsx and CameraSystem.tsx files to use the userReady property to handle loading transitions.

References

closes #insert number here

Explanation

🤖 Generated by Copilot at 59ba572

• Added userReady property to EngineState to track user avatar and camera loading (link)
• Removed metadataLoaded property from LoadingUISystemState and replaced it with userReady and sceneLoaded from EngineState (link, link)
• Set userReady to true in loadAvatarForUser function if entity is localClientEntity (link)
• Set userReady to true in CameraSystem after camera initialization (link)
• Removed unused imports of EngineActions, defineActionQueue, and dispatchAction from various files (link, link, link)
• Removed unused definitions of avatarModelChangedQueue, spectateUserQueue, and avatarModelChanged action from various files (link, link, link)
• Removed irrelevant comment from LoadingUISystem.tsx (link)

🤖 Generated by Copilot at 59ba572

userReady flag
signals camera and avatar
spring of loading done

QA Steps

List any additional steps required to QA the changes of this PR, as well as any supplemental images or videos.

Checklist

• If this PR is still a WIP, convert to a draft
• When this PR is ready, mark it as "Ready for review"
• ensure all checks pass
• Changes have been manually QA'd
• Changes reviewed by at least 2 approved reviewers