bypassImportMapForFile = async (filePath, packageDir, importMap) => {
  const initialCode = await readFile(filePath, 'utf-8');
  const adjustImportVisitor = getAdjustImportVisitor(filePath, packageDir, importMap);
  const updatedCode = transformCode(initialCode, adjustImportVisitor);
  const prettyInitialCode = await prettify(initialCode);
  const prettyUpdatedCode = await prettify(updatedCode);
  if (prettyInitialCode === prettyUpdatedCode) {
    return Promise.resolve();
  }
  return writeFile(filePath, prettyUpdatedCode);
}
Bypasses import map for a file given by `filePath`

@param {string} filePath
@param {string} packageDir
@param {object} importMap
@returns {Promise<any>}