GCode file list now automatically switches to page with newly uploaded file as soon as upload request comes back from backend as finished. Progress bar also gets emptied again then. Careful: might take a bit after the upload progress reaches 100% since the file still has to be written to disk in the backend (have to look into how to get this done in a streaming way), metadata analysis gets triggered after returning a response.

Different sorting options are still on my mental todo list ;)

Closes #34.