Update JSON with convention

[NathanMolinier]

Description

This PR update JSON sidecars according to our new convention. Only 1766/3148 json in the folder derivatives/labels will be modified by this PR. The remaining json in the folder derivatives/labels will be modified by this other PR.

The script used to generate these JSON sidecars is available here.

Examples

Example 1

Before

{
    "Author": "Sandrine Bedard",
    "Date": "2021-06-08 15:06:05"
}

After

{
    "SpatialReference": "orig",
    "GeneratedBy": [
        {
            "Name": "Manual",
            "Author": "Sandrine Bedard",
            "Date": "2021-06-08 15:06:05"
        }
    ]
}

Example 2

Before

{
    "GeneratedBy": [
        {
            "Name": "sct_register_multimodal",
            "Version": "SCT v6.1",
            "Description": "Warp from T2w discs labels"
        }
    ]
}

After

{
    "SpatialReference": "orig",
    "GeneratedBy": [
        {
            "Name": "sct_register_multimodal",
            "Version": "SCT v6.1",
            "Description": "Warp from T2w discs labels"
        }
    ]
}