chore: simplify gulp use by extracting dev & watch

[castastrophe]

Description

• Update dependencies from beta tags to latest in actionbar and divider
• Create a single gulpfile.js at root that handles building & spinning up the dev server for the current documentation site
  • Add an environment variable for the localhost URL to storybook for dev runs
• Remove bundle-builder
• Update build commands to use NX and run build in parallel across components (based on dependencies defined)
• Remove docs building from component builders

How and where has this been tested?

• yarn build:all: Builds components, site, and storybook
• yarn build:components: Builds components in parallel; uses cache [@mlogsdon18]
• yarn build:preview: Builds storybook & dependencies (all components) [@mlogsdon18]
• yarn build:site: Builds the website only [@mlogsdon18]
• yarn ci:storybook: No regressions [@mlogsdon18]
• yarn clean:components: Deletes compiled assets for all component folders [@mlogsdon18]
• yarn clean:preview: Deletes the storybook compiled assets [@mlogsdon18]
• yarn dev: Builds components & spins up live storybook & site; triggers component and assets watching [@mlogsdon18]
• yarn lint: Lints packages and css for components [@mlogsdon18]
• yarn start: Triggers storybook build and dev server [@mlogsdon18]

New commands

• yarn release: builds components and runs lerna publish --no-private
• yarn release:beta: builds components and lerna publish from-package --no-private --conventional-prerelease --preid beta --pre-dist-tag beta
• yarn release:from-package: builds components and lerna publish from-package --no-private
• yarn release:site: builds components, site, and storybook; publishes to gh-pages

Regression testing

Validate:

1. A legacy documentation page (such as accordion), including:

• The page renders correctly
• The page is accessible
• The page is responsive

2. A migrated documentation page (such as action group), including:

• The page renders correctly
• The page is accessible
• The page is responsive

To-do list

• I have read the contribution guidelines.
• I have updated relevant storybook stories and templates.
• If my change impacts other components, I have tested to make sure they don't break.
• If my change impacts documentation, I have updated the documentation accordingly.
• ✨ This pull request is ready to merge. ✨

[github-actions]

🚀 Deployed on https://pr-2099--spectrum-css.netlify.app

[pfulton]

A few things here, @castastrophe, but I think we're very close!