fix: add generate certificate method to peer connection polyfill

Adds a dummy implementation that just throws.  I don't think this is
ideal for the long term but weirdly in my app we only call this method
in browsers, but the app builds using the polyfill types so it needs
to be present.

polyfill/RTCPeerConnection.d.ts

@@ -56,4 +56,7 @@ export default class _RTCPeerConnection extends EventTarget implements RTCPeerCo
     setConfiguration(configuration: RTCConfiguration): void;
     setLocalDescription(description: RTCSessionDescriptionInit): Promise<void>;
     setRemoteDescription(description: RTCSessionDescriptionInit): Promise<void>;
+
+    // static methods
+    static generateCertificate(keygenAlgorithm: AlgorithmIdentifier): Promise<RTCCertificate>;
 }

polyfill/RTCPeerConnection.js

@@ -7,6 +7,10 @@ import RTCSctpTransport from './RTCSctpTransport.js';
 import DOMException from 'node-domexception';
 
 export default class _RTCPeerConnection extends EventTarget {
+    static async generateCertificate() {
+        throw new Error('Not implemented');
+    }
+
     #peerConnection;
     #localOffer;
     #localAnswer;