Minor ClientAnimator refactor

[tehtelev]

The following improvements have been made to the animation system:
1) ClientAnimator:

• More comments about the code logic in calculateMatrices;
• Matrix copying is done in chunks using Buffer;
• Protections have been implemented against potential errors like this issues related to array bounds violations;

2) ShapeElement:

• A working caching system for base element matrices has been implemented, significantly speeding up animation calculations for block entity animations overall (reduced from 14 seconds to 9 seconds on a 30-second benchmark). This is due to the fact that in block entity animations, only a small portion of the model elements are often animated, so there is no need to recalculate transformation matrices for non-animated elements. For entities, the increase is almost imperceptible. An increase of about 5% is only observed if the animations are made in version 1.

3) Mat4f:

• the Multiply method has been switched to unsafe pointer usage for direct memory access, resulting in speedups in busy areas.

On my test map with a large number of block entities with animations, we get the following results:

[tyronx]

hey, i don't quite understand what this flag is for. This only seems to be set to true when a ShapeElement object was created and then never again? Why not just null check the matrixes then?

bool _isCacheDirty => _cachedBaseMatrixV0==null || _cachedBaseMatrixV1==null;

[tehtelev]

Yes, I missed that moment.

[tyronx]

please no _ prefixes, we don't use these in our code base