Sprite render pipeline prepare stage

[ManevilleF]

Objective

Add a prepare stage in the sprite render pipeline.

This would allow for heavier operations like #5213 as suggested by @superdump
and compute the sprite slicing there

Concept

The objective is to keep 1-1 mapping between main world Sprite and the ExtractedSprite, but allow multiple PreparedSprite to be then computed before batching. This way the slicing, tiling, etc can be computed in the prepare stage as long as other checks which are not required in the queue stage.

  Main world   │     Render World
               │
               │
               │        Extract             Prepare                   Queue               Draw
               │
               │
 ┌────────┐    │    ┌───────────┐        ┌───────────┐
 │        │    │    │ Extracted │        │Prepared   ├─┐
 │ Sprite │ ───┼──► │ Sprite    ├───────►│Sprite     │ │    ──────►  Batching    ──────►  Draw
 │        │    │    │           │        │           │ ├──┐
 └────────┘    │    └───────────┘        └─┬─────────┘ │  │
               │                           │           │  │
               │                           └─┬─────────┘  │
               │                             │            │
               │                             └────────────┘

Work done

• Add prepare stage (fc9af23)
• Split the render pipeline in different files

Notes

• This new stage adds an extra computation which I'm not happy about, querying the GpuImage asset to retrieve the image size which is currently done in the queue stage which queries it also for the sampler and view.

• I would like to include the VisibleEntities check in the prepare stage and reduce the queue stage workload but I'm not familiar with the render phases system

• Maybe the batching could happen in the prepare stage but I'm still not sure of the implications with the render phases