Store thumbnail version for all image attachment

[nitrosx]

SciCat BE currently store the binary format of any attachment. If it the attachment is an image, the BE will always return the original size. This can result in a higher bandwidth usage if many images are requested and a lower resolution is requested.

Proposed solution:

• When BE receives a request to store an attachment, it will store the original file as blob in a document, together with a linked document containing a thumbnail version of the image or of the icon related t the content of the attachment.
• When BE receives a request to retrieve an attachment, the request should contains the format requested. Something like: original, thumbnail. The Response will contains the matching size.

In case, the attachment is not an image, we could associated a standard thumbnail defined in configuration

Alternative solution:

• upon a post, the BE will store the original file as binary blob together with the type.
• when BE receives a get, the request should contains the expected output.
  In case of an image, we could return the original, thumbnail format or width_x_height
  In case of any other type of file, we could return the original file or the matching icon in various size.