Add the possibility to delete a model (bug 1908939)

web/firefoxcom.js

@@ -320,6 +320,10 @@ class MLManager {
     return !!(await this.#enabled?.get(name));
   }
 
+  deleteModel(service) {
+    return FirefoxCom.requestAsync("mlDelete", service);
+  }
+
   guess(data) {
     return FirefoxCom.requestAsync("mlGuess", data);
   }

web/genericcom.js

@@ -52,6 +52,10 @@ class MLManager {
     return false;
   }
 
+  async deleteModel(_service) {
+    return null;
+  }
+
   async guess() {
     return null;
   }