Can only select .bcup files when importing vaults

[Soulsuke]

Hello,

I'm not sure if this is an issue or of it's intended, but there's a slight discrepancy between desktop and android apps behaviour: when adding an existing vault on android I can add a file with any or no extension, while in the desktop app only .bcup files can be selected.

To be fair, being able to hide the extension wouldn't be a bad idea