feat: Add --expand-config flag to --raw output

[estesp]

Fixes: #222

Expands the image config object in raw JSON output to allow easier inspection of image details.

[estesp]

Example output from --raw and --expand-config on amd64/alpine:latest:

{
    "schemaVersion": 2,
    "name": "amd64/alpine:latest",
    "digest": "sha256:c0669ef34cdc14332c0f1ab0c2c01acb91d96014b172f1a76f3a39e63d1f0bda",
    "os": "linux",
    "architecture": "amd64",
    "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
    "config": {
        "created": "2023-05-09T23:11:10.132147526Z",
        "architecture": "amd64",
        "os": "linux",
        "config": {
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/sh"
            ]
        },
        "rootfs": {
            "type": "layers",
            "diff_ids": [
                "sha256:bb01bd7e32b58b6694c8c3622c230171f1cec24001a82068a8d30d338f420d6c"
            ]
        },
        "history": [
            {
                "created": "2023-05-09T23:11:10.007217553Z",
                "created_by": "/bin/sh -c #(nop) ADD file:7625ddfd589fb824ee39f1b1eb387b98f3676420ff52f26eb9d975151e889667 in / "
            },
            {
                "created": "2023-05-09T23:11:10.132147526Z",
                "created_by": "/bin/sh -c #(nop)  CMD [\"/bin/sh\"]",
                "empty_layer": true
            }
        ]
    },
    "layers": [
        {
            "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
            "digest": "sha256:8a49fdb3b6a5ff2bd8ec6a86c05b2922a0f7454579ecc07637e94dfd1d0639b6",
            "size": 3397490
        }
    ]
}

[marcosnils]

:rocket: thx for taking this one so quickly