Add support for es6 modules in boot scripts

[klarkc]

Description

Add support for compiled es6 modules in boot scripts

Related issues

• connect to Support for Typescript/Babel emitted ES2015 modules #250
• connect to Add support for ES6 style async boot scripts (2.x) #252
• connect to Add support for ES6 style async boot scripts #253
• connect to Adding UMD support to help allow Typescript #203
• connect to The ability to use UMD modules for model code and boot scripts #202

Checklist

• New tests added or existing tests modified to cover all changes
• Code conforms with the style
  guide

[slnode]

Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

[virkt25]

ok to test

[klarkc]

There are errors coming from master, should I try to fix them?

[virkt25]

If you can that would be great :)

[bajtos]

Rebased on top of the latest master. The tests are passing locally for me, let's see what our CI thinks.

@klarkc FWIW, there are more places than just boot scripts where we may need to recognize ES6 default exports - see #250. I am ok to fix those other places incrementally as users start asking for that.

[bajtos]

Landed 🎉 Thank you @klarkc for your first contribution! ❤️

Because you send the PR from your master branch, you will need a bit of cleanup work on your side to make your master branch up to date with our master branch (the upstream).

1. If you don't have strongloop's repository configured as an upstream remote yet:

   $ git remote add upstream https://github.com/strongloop/loopback
   

2. Fetch the latest updates from upstream:

   $ git fetch upstream
   

3. Hard-reset your master to upstream:

   $ git checkout master
   $ git reset --hard upstream/master
   

4. Force-push your changes back to GitHub

   $ git push -f
   

In the future, please create a new feature branch for each pull request. I recommend the following guide for step-by-step instructions showing the recommended contribution workflow: https://www.nearform.com/blog/first-time-with-open-source/