[feat] update some feature

sync code of  fastrtc,
add text support through datachannel,
fix safari connect problem
support chat without camera or mic

frontend/shared/VideoChat/utils.ts

@@ -0,0 +1,28 @@
+export function click_outside(node: Node, cb: any): any {
+  const handle_click = (event: MouseEvent): void => {
+    if (
+      node &&
+      !node.contains(event.target as Node) &&
+      !event.defaultPrevented
+    ) {
+      cb(event);
+    }
+  };
+
+  document.addEventListener("click", handle_click, true);
+
+  return {
+    destroy() {
+      document.removeEventListener("click", handle_click, true);
+    },
+  };
+}
+
+export function insertStringAt(rawStr: string, insertString: string, index: number) {
+  if (index < 0 || index > rawStr.length) {
+      console.error("索引超出范围");
+      return rawStr;
+  }
+
+  return rawStr.substring(0, index) + insertString + rawStr.substring(index);
+}