Trying to query subfolders from folders with umlauts (Ä Ö Ü ß) leads to an exception "Bad Command 11"

[mhpcc]

Describe the bug
The Client uses full_name of a folder instead of path of a folder to query for subfolders. This leads to exceptions if there are umlauts (mutated vowels) in the parent folder name.

Used config
Default.

Code to Reproduce
The troubling code section which produces the reported bug.

$this->connection->folders('Gel&APY-schte Elemente/%'); // works with $folder->path
$this->connection->folders('Gelöschte Elemente/%'); // exception with $folder->full_name

I'm not sure if changing this to $folder->path creates any issues, so I didn't create a PR. It certainly prevents the exceptions though.