Refactored multiple classes

Refactored UnlockWorkflow, CustomMountPointChooser, DokanyVolume and UnlockInvalidMountPointController

Changed UnlockWorkflow#handleGenericError() to accept Throwables

Added check for parent to CustomMountPointChooser (when using FUSE on Win)

Removed legacy constant from DokanyVolume

Added asserts to UnlockInvalidMountPointController and UnlockWorkflow

main/commons/src/main/java/org/cryptomator/common/mountpoint/CustomMountPointChooser.java

@@ -46,6 +46,10 @@ public class CustomMountPointChooser implements MountPointChooser {
 			//This the case on Windows when using FUSE
 			//See https://github.com/billziss-gh/winfsp/issues/320
 
+			Path parent = mountPoint.getParent();
+			if (!Files.isDirectory(parent)) {
+				throw wrapAsIMPE(new NotDirectoryException(parent.toString()));
+			}
 			//We must use #notExists() here because notExists =/= !exists (see docs)
 			if (!Files.notExists(mountPoint, LinkOption.NOFOLLOW_LINKS)) {
 				//File exists OR can't be determined

main/commons/src/main/java/org/cryptomator/common/vaults/DokanyVolume.java

@@ -22,7 +22,6 @@ import java.util.concurrent.ExecutorService;
 public class DokanyVolume implements Volume {
 
 	private static final Logger LOG = LoggerFactory.getLogger(DokanyVolume.class);
-	private static final int MAX_TMPMOUNTPOINT_CREATION_RETRIES = 10;
 
 	private static final String FS_TYPE_NAME = "Cryptomator File System";