Collection thumbnail uploader

[smohiudd]

Description

Thumbnails in STAC collections are stored in a MCP s3 bucket (s3://veda-thumbnails/) that is then served by a cloudfront url:

    "assets": {
      "thumbnail": {
          "title": "Thumbnail",
          "description": "Photo by [Jonny Glessner](https://x.com/JonnyGlessner/status/1768424574855610777/photo/4) (Wedge tornado passing southeast of Wapakoneta, Ohio on March 14, 2024)",
          "href": "https://thumbnails.openveda.cloud/tornado-2024-cover.png",
          "type": "image/jpeg",
          "roles": ["thumbnail"]
      }
    },

Not all users have access to the MCP bucket so we need to allow the capability for a user to upload a thumbnail to the bucket that can then be referenced in the STAC collection.

Acceptance Criteria

• A user is able to upload a thumbnail image using the interface to the S3 bucket