Fix for bug #8354 (#8379)

* The nano to milli second conversion was wrong so updated it

* extension is a string array accoring to W3 APIs but here it is defined as array of Object

* Endpoint needs to be corrected as well so made the changes as per the document

packages/wdio-protocols/protocols/webdriver.json

@@ -1173,7 +1173,7 @@
       }]
     }
   },
-  "/session/:sessionId/authenticator": {
+  "/session/:sessionId/webauthn/authenticator": {
     "POST": {
       "command": "addVirtualAuthenticator",
       "description": "Creates a software [Virtual Authenticator](https://www.w3.org/TR/webauthn-2/#virtual-authenticators).",
@@ -1210,7 +1210,7 @@
         "required": false
       }, {
         "name": "extensions",
-        "type": "object[]",
+        "type": "string[]",
         "description": "",
         "required": false
       }, {