Redundant buffer bindings on metal when only changing vertex buffer offset

[staminajim]

In metal, if you send commands which only change the vertex buffer offset, (ie. not binding a different buffer) you get lots of warnings about unnecessary bindings in Xcode. This is pretty common when using shared resource pools.

According to the Apple documentation you should use setVertexBufferOffset instead of setVertexBuffer on the render encoder: https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/MTLBestPracticesGuide/BufferBindings.html

Incoming PR which I'm using in my engine which resolves this