Add byte stride to metadata binary encoding for better GPU alignment

[lilleyse]

Property values should be well aligned for GPU architectures.

The one case we brainstormed a few weeks back is a color property like an RGB8

Class property

"color": {
  "type": "ARRAY",
  "componentType": "UINT8",
  "componentCount": 3
}

Property table

"color": {
  "bufferView": 0
}

If the data was packed tightly it would poorly aligned and either the client or driver would need to shuffle data to add padding so that each color is aligned to 4-bytes. glTF has rules that enforce good alignment like this and we should consider adding something similar. One way glTF accomplishes this is through a stride property

Property table

"color": {
  "bufferView": 0,
  "stride": 4
}

The rules get trickier when we have strings, arrays with greater than 4 elements, or arrays of variable size.