Refactor: form builder to use wp-scripts

[jonwaldstein]

Description

This updates the form builder build process to use wp-scripts when loaded from the plugin. This is necessary to offload dependency management to WordPress for use with custom external blocks.

Affects

The form builder will not use the WordPress installation to load dependencies / gutenberg scripts. Some imports that were coming directly from a package that is not publicly exposed were relocated and/or forked.

The main noticeable difference here is the secondary sidebar / block inserter. It was too much of a rabbit hole to fork the components we were using so it is now simplified with the <Library /> component that WP core and the isolated editor are using.

Visuals

Testing Instructions

• Pull branch and run `npm install && npm run build'
• Open or create a next gen form and use the builder
• Everything should work the same except the block inserter/secondary sidebar which only shows child blocks when cursor is selecting section inner blocks in canvas.

Pre-review Checklist

• Acceptance criteria satisfied and marked in related issue
• Relevant @unreleased tags included in DocBlocks
• Includes unit tests
• Reviewed by the designer (if follows a design)
• Self Review of code and UX completed

[jonwaldstein]

@kjohnson this is ready for review.

[kjohnson]

Looks good to me.