Synchronize scripts with Vulkan and correct extension appendix section nesting

The observable effects of this are

- Pushes the subsection titles in the extension appendices down one level, similar to #1087 but keeping the scripts in sync
- Adds an autogenerated 'API Interactions' section with currently only affects the cl_khr_command_buffer extension, since that's the only one with some APIs tagged in the XML as dependent on a particular core version