[Feature] Add endpoint for getting data about a given document

[kevinanielsen]

Is your feature request related to a problem? Please describe.

N/A

Describe the solution you'd like

Add an endpoint for getting more information about an document based on the filename /api/cdn/doc/:filename
This data needs to contain width, height, file size (in bytes), filename, download-url, and more relevant information.

A 200 response could look like this:

{
  "filename": "string",
  "download_url": "string",
  "file_size": "int",
}

Describe alternatives you've considered

N/A

Additional context

N/A