Add setOption to pageconfig module

packages/coreutils/src/pageconfig.ts

@@ -82,6 +82,21 @@ namespace PageConfig {
     }
     return configData[name] || '';
   }
+  
+  /**
+   * Set global configuration data for the Jupyter application.
+   *
+   * @param name - The name of the configuration option.
+   * @param value - The value to set the option to.
+   *
+   * @returns The last config value or an empty string if it doesn't exist.
+   */
+  export
+  function setOption(name: string, value: string): string {
+    let last = getOption(value);
+    configData[name] = value;
+    return last;
+  }
 
   /**
    * Get the base url for a Jupyter application.