Import Filament inventory#138

I’d like to migrate from Octoprint to SimplyPrint for the single Ender 3 V2 printer I currently use (adding an A1 shortly) and I have been using the Spool Manager plugin for tracking filament use.

Rather than manually entering the 30+ filament rolls I have it would be nice if you could import from a CSV file into SimplyPrint.

Great idea!