New and better state context provider

[alvarosabu]

Description

Based on https://github.com/orgs/Tresjs/discussions/321

As a plugin author, I will like to have a reactive state with the following characteristics:

• Performant, (use of shallowRef where needed)
• read-only
• Strictly Typed
• Reduce side effects on watchers
• Needs to work on cientos and the rest of ecosystem via provide/inject

Suggested solution

Name	Type	Requirement	Details
scene	readonly, shallowRef	essential
cameras	readonly, shallowRef	essential	userData.TRES_IS_ACTIVE_CAMERA = true const cameras = shallowRef([]) return { cameras: readonly(cameras)}
camera	computed, readonly	essential
pushCamera(newCamera: Camera, setActive: boolean)	function	essential	cameras should be watched and removed from the cameras array if they got removed from the scene
removeCamera(camera: Camera)	function	essential
setCamera(cameraId string)	function	essential
renderer	readonly, shallowRef	essential	setRenderer(renderer: Renderer) maybe only callable once?
setRenderer(renderer: Renderer)	function	essential
sizes (height, width, aspectRatio)	readonly	handy	sizes: {     height: Ref     width: Ref     aspectRatio: Computed }

Alternative

No response

Additional context

No response

Validations

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