Fix for softlocks when initializing/exiting the application and minor issues with backup/restore

[w3irDv]

This PR address the following problems:

• Crash when initializing the application if savedata for a installed title is stored in nand and in usb ( PR)
• Crash when exiting the application (PR)
• Comon savedata is not always detected when performing backup/restore from user to user
• Restore from/to specific user creates fake folders
• copyToOtherDevice fails if allusers is selected

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Some technical detail about the fixes:

• Detailed explanations for the two first issues can be found in the referenced PR.
• Common savedata issue is due to a problem in the condition to detect empty directories.
• Fake folders issue is due to the default creation of quotas for all source users even if from/to user option is selected
• copySavedata don't take into account the allusers option that can be selected from the menu

I will appreciate if you can review the code. Any comment will be appreciated.

[Lenochxd]

Working great! Thanks :)