…ler to reboot

allow users to wait for tasks, or receive an awaitable task in return
support async core tasks module
wait for synchronous file operations by default
no wait for asynchronous file operations by default (return awaitable task class object instead)
update all modules that use a task, unit-tests and docs

validate destination on upload and throw exceptions
when uploading files to the root of the cloud drive
when uploading a file with invalid characters

update direct-io exceptions on metadata errors
raise error on folder not found
reduce duplicate direct-io object