Explore generation with C++26 reflection

This is a slightly more frivolous issue, and I hope to kickstart some discussion.

How would we write/rewrite the generator with C++26 reflection? Could we model _everything_ that we currently generate? The current generator works entirely in the XML type/string domain (especially when it comes to the various snippets) with not much typed knowledge about the Vulkan specification besides the structs generated on-the-fly.

No files or tests are named. Start by examining the current generator's XML type/string representation, generated snippets, Vulkan specification knowledge, and on-the-fly structs; done would be a concrete assessment or design for which generation responsibilities C++26 reflection could model.

Written by the indexing model from the issue text.