Add new use resources methods

[mxpv]

This PR:

• Changes MTLRenderStages to bitflags as there are cases when we want to combine stages (below).
• Current useResource method is deprecated. The new one includes stages param.
• Adds useResources and useHeaps to pass slices of resources.
• Updates argument-buffer example to demonstrate how to use use_resources.
• Adds new bindless example that demonstrates how to bind lots of textures all at once with argument buffers.