do not error when processing sources that include node hashbang

[iambumblehead]

cc @koshic @tommy-mitchell re #215

this PR removes the hashbang line from the sources before prepending import expressions, then re-adds any hashbang line to the final result returned by the loader

[iambumblehead]

@tommy-mitchell thank you for giving esmock your valuable attention. Feel free to leave any comments or advice.

This PR builds on the test from your earlier PR

[iambumblehead]

this test is failing in windows and maybe a different PR should resolve it. It relates to filesystem paths

"test-metaresolve": "rimraf dist && tsc && cross-env \"NODE_OPTIONS=--experimental-import-meta-resolve --loader=esmock\" NODE_NO_WARNINGS=1 ava",

[iambumblehead]

the win32 could probably be resolved soon, but slow internet speeds here make it difficult to setup a windows virtual machine to run tests with latest node 18

[tommy-mitchell]

I have a Windows x64 machine, would that work for reproducing? I could try resolving it

[iambumblehead]

@tommy-mitchell that would be great. Here is where I think the problem is. I think import.meta.resolve is returning the path n the wrong format

const resolve = isMetaResolve ?
  (import.meta.resolve.constructor.name === 'AsyncFunction'
    ? async (id, p) => import.meta.resolve(id, asFileURL(p))
      .catch(() => resolvewith(id, p))
    : (id, p) => {
      try { return import.meta.resolve(id, asFileURL(p)) }
      catch { return resolvewith(id, p) }
    })
  : resolvewith

cd into the tests-source-map folder and npm install then npm test to run the tests

[iambumblehead]

possibly related nodejs/node#35518

[iambumblehead]

Pinning the node version number to 18.16 resolved the pipeline error. A ticket for that node 18.17 issue is created here nodejs/node#48948 and so this PR for hashbang support is complete and ready for review

[iambumblehead]

if anyone has retro-active review comments feel free to leave those