Ref: OM41 / DECOM-26

Is your feature request related to a problem? Please describe.
As an administrator I want to add images to text areas so the contents in my instance are prettier.

Describe the solution you'd like
To be able to upload images in the WYSIWYG editor. These images should be uploaded as attachments through Carrierwave/ActiveStorage or the current attachment storage that we use.

I would also like to be able to resize and drag and drop images.

Describe alternatives you've considered
QuillJS supports base64 by default but we don't want that for performance reasons. See #4595 and #5364.

As a workaround at the moment the way that administrators have for doing this is by drag and dropping. See an example in Barcelona Participatory Budgeting process.

Additional context
This is already done with the DecidimAwesome module. With this feature we would support this by default.

Does this issue could impact on users private data?
No, it's about adding images.

Acceptance criteria

• As an administrator I can upload images with any WYSIWYG editor, for instance in the description of a Participatory Process
• As a visitor these images are uploaded to the static files server, not with base64
• As an administrator when after I've uploaded an image I can resize it
• As an administrator I can upload an image by drag and dropping it from my computer
• As an administrator I can't upload a PDF document from this file upload