* Remove I/O from backup create() function
* Move mount check into exectutor thread
* Remove I/O from backup open() function
* Remove I/O from _folder_save()
* Refactor remove_folder and remove_folder_with_excludes
Make remove_folder and remove_folder_with_excludes synchronous
functions which need to be run in an executor thread to be safely used
in asyncio. This makes them better composable with other I/O operations
like checking for file existence etc.
* Fix logger typo
* Use return values for functions running in an exectutor
* Move location check into a separate function
* Fix extract
