Refresh the Swift Package Registry OpenAPI document (#8096)

### Motivation:

The OpenAPI document for Swift Package Registry was incomplete and
didn't contain all the requirements described in the related Swift
Evolution proposals.

### Modifications:

Rewrote the OpenAPI document based on the current reading of all the
Swift Package Registry Swift Evolution proposals and documentation in
this repository.

You can view the rendered version of the docs at:
https://editor.swagger.io/?url=https://raw.githubusercontent.com/czechboy0/swift-package-manager/refs/heads/hd-refresh-registry-openapi/Documentation/PackageRegistry/registry.openapi.yaml

### Result:

A much more accurate OpenAPI doc, one that can be used for code
generation.

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Co-authored-by: Paul LeMarquand <[email protected]>

Author: czechboy0