Make "Pick image file" more accessible

[bugbrekr]

The "Pick image file" button lets users pick a saved image file from their device to scan for codes.

This feature is used frequently - equal to or more than the "Compose barcode" button - and it should hence be placed on the main (scanning) screen, instead of its current location which is hidden inside a "More" icon ( ⋮ ).

This simple enhancement will make the daily experience for any user a lot better.