Audit errors raised during manifes/manifest list push

Compare our behavior to dockerhub and update where necessary https://github.com/distribution/distribution/blob/d80a63f1eaa215246eee566f4426d2f2ceecc06e/registry/api/v2/errors.go

HTTP/1.1 400 Bad Request
content-length: 237
content-type: application/json
date: Thu, 10 Mar 2022 13:45:35 GMT
docker-distribution-api-version: registry/2.0
docker-ratelimit-source: 86.49.250.169
strict-transport-security: max-age=31536000

{
    "errors": [
        {
            "code": "MANIFEST_INVALID",
            "detail": "mediaType in manifest list should be 'application/vnd.docker.distribution.manifest.list.v2+json' not 'application/vnd.docker.distribution.manifest.v2+json'",
            "message": "manifest invalid"
        }
    ]
}




HTTP/1.1 400 Bad Request
content-length: 625
content-type: application/json
date: Thu, 10 Mar 2022 13:46:32 GMT
docker-distribution-api-version: registry/2.0
docker-ratelimit-source: 86.49.250.169
strict-transport-security: max-age=31536000

{
    "errors": [
        {
            "code": "MANIFEST_BLOB_UNKNOWN",
            "detail": "sha256:b5b2b2c507a0944348e0303114d8d93aaaa081732b86451d9bce1f432a537bc7",
            "message": "blob unknown to registry"
        },
        {
            "code": "MANIFEST_BLOB_UNKNOWN",
            "detail": "sha256:e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7fc331f",
            "message": "blob unknown to registry"
        },
        {
            "code": "MANIFEST_BLOB_UNKNOWN",
            "detail": "sha256:3c3a4604a545cdc127456d94e421cd355bca5b528f4a9c1905b15da2eb4a4c6b",
            "message": "blob unknown to registry"
        },
        {
            "code": "MANIFEST_BLOB_UNKNOWN",
            "detail": "sha256:ec4b8955958665577945c89419d1af06b5f7636b4ac3da7f12184802ad867736",
            "message": "blob unknown to registry"
        }
    ]
}

Start by locating the current manifest and manifest-list push error handling, then compare its responses with the referenced Docker Distribution errors.go and the Docker Hub examples in this issue. Done means the relevant error codes, messages, details, and response behavior match the intended Docker Hub behavior, with coverage added or updated where the repository supports it.