Charts: add skeleton for a new JS package

[jeherve]

Proposed changes:

This package can then be used by multiple teams to handle charts within Automattic properties.

• [x] I created the matching mirror repo already.

Other information:

• [ ] Have you written new tests for your changes, if applicable?
• [ ] Have you checked the E2E test CI results, and verified that your changes do not break them?
• [ ] Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

• pfKYZu-1Jg-p2#comment-1530

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

Not much to test yet. Is CI happy?

[github-actions[bot]]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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[github-actions[bot]]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the add/charts-js-package branch.
  • For jetpack-mu-wpcom changes, also add define( 'JETPACK_MU_WPCOM_LOAD_VIA_BETA_PLUGIN', true ); to your wp-config.php file.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack add/charts-js-package

  bin/jetpack-downloader test jetpack-mu-wpcom-plugin add/charts-js-package

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[jeherve]

@Automattic/jetpack-garage I had to push a few additional changes after running the generate command. I think it may be worth updating generate so those are created right off the bat?