feat: implement coordinate extraction from metadata

[rmm-ch]

Images can have GPS info in the exif metadata. Currently we are not extracting this info. It is possible with PIL, for example.

• note: need to handle the case where this metadata is missing of course. Currently the user has to manually specify the location in the input sidebar, the function to lookup should fail gracefully and interact properly with the manual option.

[rmm-ch]

• a design decision: if metadata is present, should the user be allowed to override it?
  (this decision is about the UI flow, and not about implementing the extraction itself)