[FEATURE REQUEST] Add more PDF paper size options

[stbxxl]

Is your feature request related to a problem? Please describe. Currently they are 3 paper size options (Full, A4, A3). However, here in the United States, all formal papers come in the US Letter size. If I scan a US Letter sized document and select A4 as paper size (closest option), I always get a white frame around the scan.

Describe the solution you'd like Add more paper size options. For example US Letter (612 x 792 pixels) and ideally an additional custom option where the user can set the aspect ratio and/or the xy pixel count.

Describe alternatives you've considered Other PDF scanning apps offer more page size formats. The only way to get US Letter sizes scans with the current version would be to export and than crop the file to US Letter size.

Additional context Add any other context or screenshots about the feature request here.

[farfromrefug]

@stbxxl it is released (in review on the stores)