Split spec into multiple files for easier patching

[displague]

In metal-java, metal-go, etc the upstream API spec is pulled as separate files and those files are captured in the SDK repo. Patches are easier to apply because the files are smaller and the patch is applied to a specific file (component schema or path) rather than a hunk within the large file. For this project, if we can not pull down an unstitched copy of the spec, we could use OAS3 tools to split the spec into multiple files.