Add support for VK_PRIMITIVE_TOPOLOGY_TRIANGLE_FAN.

[billhollings]

To reduce complexity and repetitive copy-pasted spaghetti code, the design approach here was to implement triangle fan conversion on MVKCmdDrawIndexedIndirect, as the most general of the draw commands, and then populate and invoke a synthetic MVKCmdDrawIndexedIndirect command from the other draw commands.

• Rename pipeline factory shader cmdDrawIndexedIndirectMultiviewConvertBuffers() to cmdDrawIndexedIndirectConvertBuffers(), and in addition to original support for modifying indirect content to support multiview, add support for converting triangle fan indirect content and indexes to triangle list.

• Modify MVKCmdDrawIndexedIndirect to track need to convert triangle fans to triangle list, and invoke kernel function when needed.

• Modify MVKCmdDraw, MVKCmdDrawIndexed, and MVKCmdDrawIndirect to populate and invoke a synthetic MVKCmdDrawIndexedIndirect command to convert triangle fans to triangle lists.

• Add pipeline factory shader cmdDrawIndirectPopulateIndexes() to convert non-indexed indirect content to indexed indirect content.

• MVKCmdDrawIndexedIndirect add support for zero divisor vertex buffers potentially coming from MVKCmdDraw and MVKCmdDrawIndexed.

• Rename pipeline factory shader cmdDrawIndexedIndirectConvertBuffers() to cmdDrawIndexedIndirectTessConvertBuffers() so it will be invoked from MVKCommandEncodingPool::getCmdDrawIndirectTessConvertBuffersMTLComputePipelineState() (unrelated).

Fixes #1419.
Fixes #1799.

[billhollings]

@cdavis5e As described above in the PR description , the implementation here delegates from MVKCmdDraw, MVKCmdDrawIndexed, and MVKCmdDrawIndirect, to a synthetic MVKCmdDrawIndexedIndirect instance, whenever the topology is triangle fans. I did this to avoid having to duplicate the conversion code across all of the draw commands.

It got me to contemplating whether a similar approach might be useful for the entire tessellation draw flow. Basically, implement any non-native-Metal workflow(s) once in MVKCmdDrawIndexedIndirect, and delegate from the other draw commands, leaving those draw commands to just handle behaviour that Metal supports natively.

Thoughts about the practicality of such an approach? You know the tess implementation much better than I do.

[IsaacMarovitz]

Can confirm this fixes the UI in No Man's Sky!