Ring buffer for SkinInstance

[AlexAPPi]

Solution: #8020

PR Description

This PR introduces a ring buffer for SkinInstance, used when updating the bone matrix texture.
Instead of a single buffer that could cause frequent GPU stalls during data uploads, the system now uses a multi-slot ring buffer across frames.

Main Changes

• Implemented a ring buffer to store bone matrices, allowing updates to be written into independent slots per frame.
• Bone texture updates no longer wait for the previous frame to complete, reducing the risk of GPU stalls.
• Updated SkinInstance logic to pick the active ring buffer slot based on the current render frame.
• Added configurability for the number of ring buffer slots (default is 1).

Results

• Reduced GPU blocking during bone data uploads.
• More stable frame times when animating many characters simultaneously.
• Lowered latency between CPU → GPU updates.
• This update is fully backward-compatible and does not affect existing behavior.

I have read the contributing guidelines

[mvaligursky]

I developed UploadStream internal API to help with CPU->GPU uploads here: #8053

And so I'm keen to use this for Skin/Batch Instances as well. Which means first switching those to use StorageBuffer instead of texture.