GUI v2: Default settings

[apyrgio]

Main issue: #885

Repurpose the existing settings window, which appears when a user selects a document, with a settings window that lists the default settings for Dangerzone. Add the following settings:

• [ ] The suffix that will be appended at the name of the sanitized file (default: safe)
• [ ] The folder name where the original document will be moved (default: unsafe/)
• [ ] Whether to open safe documents after processing
  • [ ] (Linux-only) The PDF application that will be used for opening the sanitized documents
• [ ] Make Dangerzone the default app to open office documents and images: :exclamation: Placeholder, we don't have a user story for this yet.
• [ ] Whether to perform OCR on the sanitized file
  • [ ] The language that will be used

Finally, override the footer (see #886) and add the following options:

• [ ] Reset the settings to the factory defaults
• [ ] Save the selected settings

The design material misses the following:

• [ ] An alert popup about resetting the settings.
• [ ] A confirmation that the settings have been successfully saved (✔️)
• [ ] A button to go back to the main menu (⮐)

Design material

Default settings window

Existing settings window

[DeltaEpsilon19498]

When I use the GUI and select where to save the safe documents to (I do not use an unsafe directory), it defaults to saving in the same directory each time. What I prefer to do is to save it in a "safe" directory (as opposed to moving the original file to an unsafe directory). This requires that I have to navigate the file system to choose my "safe" directory each time I open dangerzone. It is not a big deal, but it would be nice if the GUI would have a way to default to saving in this "safe" directory instead of having the user choose it manually each time.