glGetVertexArrayIndexediv() missing VERTEX_ATTRIB_BINDING

`GetVertexAttrib*()` exposes queries to currently bound vertex array, to these properties:

- `VERTEX_ATTRIB_ARRAY_BUFFER_BINDING`
- `VERTEX_ATTRIB_ARRAY_ENABLED`
- `VERTEX_ATTRIB_ARRAY_SIZE`
- `VERTEX_ATTRIB_ARRAY_STRIDE`
- `VERTEX_ATTRIB_ARRAY_TYPE`
- `VERTEX_ATTRIB_ARRAY_NORMALIZED`
- `VERTEX_ATTRIB_ARRAY_INTEGER`
- `VERTEX_ATTRIB_ARRAY_LONG`
- `VERTEX_ATTRIB_ARRAY_DIVISOR`
- `VERTEX_ATTRIB_BINDING`
- `VERTEX_ATTRIB_RELATIVE_OFFSET`
- `CURRENT_VERTEX_ATTRIB`

Meanwhile `GetVertexArrayIndexed()` provides query to specific vertex array without needing to bind it to make the query. However, the list of queriable properties appears to be missing `VERTEX_ATTRIB_BINDING`:

- `VERTEX_ATTRIB_ARRAY_BUFFER_BINDING`
- `VERTEX_ATTRIB_ARRAY_ENABLED`
- `VERTEX_ATTRIB_ARRAY_SIZE`
- `VERTEX_ATTRIB_ARRAY_STRIDE`
- `VERTEX_ATTRIB_ARRAY_TYPE`
- `VERTEX_ATTRIB_ARRAY_NORMALIZED`
- `VERTEX_ATTRIB_ARRAY_INTEGER`
- `VERTEX_ATTRIB_ARRAY_LONG`
- `VERTEX_ATTRIB_ARRAY_DIVISOR`
- `VERTEX_ATTRIB_RELATIVE_OFFSET`
- `VERTEX_BINDING_STRIDE`
- `VERTEX_BINDING_DIVISOR`
- `VERTEX_BINDING_BUFFER`

What happened to `VERTEX_ATTRIB_BINDING`?

It looks like at least MESA driver supports `GetVertexArrayIndexed(VERTEX_ATTRIB_BINDING)` query, but not some other drivers.

Start by comparing the GetVertexArrayIndexed() query list with the GetVertexAttrib*() properties described in the issue and the relevant OpenGL specification. Determine whether VERTEX_ATTRIB_BINDING is intended to be supported, then document the specification or registry change needed and account for the driver behavior noted in the report.

Written by the indexing model from the issue text.