List mappings which starts from lhs.

import { Denops } from "../mod.ts";
import * as mapping from "../mapping/mod.ts";

export async function main(denops: Denops): Promise<void> {
  const result = await mapping.list(denops, "<Plug>");
  console.log(result);
  // [
  //   {
  //     mode: "",
  //     lhs: "<Plug>(...)",
  //     // ...
  //   },
  //   // ...
  // ]
}