message: Add option to configure helper name for date plugin
  Make date filter configurable via plug-in option.
  Add test to check that date helper can be accessed with custom name.
diff: @@ -12,6 +12,10 @@ const formats = new Map([
  ]);
  export interface Options {
  +
  + /** The name of the helper */
  + name: string;
  +
  /** The loaded locales */
  locales: Record<string, unknown>;
  @@ -21,6 +25,7 @@ export interface Options {
  // Default options
  const defaults: Options = {
  + name: "date",
  locales: {},
  formats: {},
  };
  @@ -31,7 +36,7 @@ export default function (userOptions?: Partial<Options>) {
  const defaultLocale = Object.keys(options.locales).shift();
  return (site: Site) => {
  - site.filter("date", filter as Helper);
  + site.filter(options.name, filter as Helper);
  function filter(
  date: string | Date,
  