Use the convert-to-es-modules package from the frontend-toolkit repo to
convert CommonJS/Node require syntax to ES modules.

As well as the module syntax conversion, this script also has the effect
of normalizing the sorting and grouping of imports according to the
following convention:

 - Imports are grouped into 3 categories: Vendor, same package but other
   directory (as calling module), same directory as calling module
 - Imports are sorted by module path

Import specifiers are untouched.