export new/experimental webpack bundler

[purplecabbage]

Description

This is experimental. !!!
In the process of removing our very large dependency on parceljs, the approach was to support webkit + parcel for a while.

Related Issue

makes use of this export, and hides it behind a flag.
adobe/aio-cli-plugin-app#610

Motivation and Context

parcel is big, and while we love it, it affects the install time of the cli. parcel is our biggest dependency.

How Has This Been Tested?

with a sample project

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[purplecabbage]

Tests are failing ... and I am out for awhile

[purplecabbage]

This is still a draft because I don't think we should do this here, but I want to keep this example code around until we find a better home for it ...
Ideally I think alternate bundlers belong in hook implementations and should be added to a project via the generator.