vfs/vfscache: fix silent write failure when mounting with remote:.

When mounting with 'remote:.' (dot notation for current directory),
the '.' is passed through toOSPath() which encodes it to full-width
'.' (U+FF0E) via EncodeDot. This caused the VFS cache data/meta root
to be written to a full-width-dot directory while the local cache
backend pointed to the canonicalized path, resulting in writes being
cached but never uploaded.

Fix by calling clean() on the relativeDirPath before toOSPath(),
so path.Clean() strips the trailing '/.' removing the dot before
encoding.

vfs/vfscache/cache.go

@@ -97,6 +97,7 @@ func New(ctx context.Context, fremote fs.Fs, opt *vfscommon.Options, avFn AddVir
 		}
 	}
 	relativeDirPath = fremote.Name() + "/" + relativeDirPath
+	relativeDirPath = clean(relativeDirPath)
 	relativeDirOSPath := toOSPath(relativeDirPath)
 
 	// Create cache root dirs