feat(client): Implement default upload folder setting

Resolve #5985

src/client/scripts/select-drive-folder.ts

@@ -0,0 +1,13 @@
+import DriveWindow from '../components/drive-window.vue';
+
+export function selectDriveFolder($root: any, multiple) {
+	return new Promise((res, rej) => {
+		const w = $root.new(DriveWindow, {
+			type: 'folder',
+			multiple
+		});
+		w.$once('selected', folders => {
+			res(multiple ? folders : (folders.length === 0 ? null : folders[0]));
+		});
+	});
+}