fix(esm): use file extension and directory index

[snyamathi]

This PR is tangential to #1727 and attempts to allow ESM to be used by fixing issues with mandatory-file-extensions.

For ES Modules, we need to specify /index.js when requiring a directory and .js when requiring a file without the use of one of the experimental flags.

The following template was compiled with the meta option disabled ( which uses __filename; also not supported by ESM ).

$ const foo = 'bar';
<h1 data-foo=foo>Hello World</h1>

  // Compiled using marko@5.17.3 - DO NOT EDIT
- import { t as _t } from "marko/src/runtime/html/index.js";
+ import { t as _t } from "marko/src/runtime/html/index.js";
  
  const _marko_componentType = "components/hello-world.marko",
        _marko_template = _t(_marko_componentType);
  
  export default _marko_template;
- import _marko_attr from "marko/src/runtime/html/helpers/attr";
+ import _marko_attr from "marko/src/runtime/html/helpers/attr.js";
- import _marko_renderer from "marko/src/runtime/components/renderer";
+ import _marko_renderer from "marko/src/runtime/components/renderer.js";
  const _marko_component = {};
  _marko_template._ = _marko_renderer(function (input, out, _componentDef, _component, state) {
    out.w(`<h1${_marko_attr("data-foo", input.bar)}>`);
    out.w("Hello World");
    out.w("</h1>");
  }, {
    t: _marko_componentType,
    i: true,
    d: true
  }, _marko_component);

This is only one portion of what would be required to support ES Modules, but it's a start 😄

[snyamathi]

Duplicate of: #1728