Charts: Adding a theme provider

[grzegorz-cp]

Fixes https://github.com/Automattic/jetpack-roadmap/issues/2041

Proposed changes:

• extending Automattic Charts with a theme provider, allowing for easier chart adoption
• replacing hard-coded colours in the chart components

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

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

Testing instructions:

• install Jetpack packages if needed (this PR doesn't add new packages) pnpm i
• navigate to the directory and run storybook: cd projects/js-packages/charts and pnpm run storybook
• verify that existing charts are working and new theme provider is available
• verify that different themes load different colours

[github-actions]

Thank you for your PR!

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

• ✅ Include a description of your PR changes.
  
• 🔴 Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• 🔴 Add a "[Type]" label (Bug, Enhancement, Janitorial, Task).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

---

The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Choose a review path based on your changes:
   • A. Team Review: add the "[Status] Needs Team Review" label
     • For most changes, including minor cross-team impacts.
     • Example: Updating a team-specific component or a small change to a shared library.
   • B. Crew Review: add the "[Status] Needs Review" label
     • For significant changes to core functionality.
     • Example: Major updates to a shared library or complex features.
   • C. Both: Start with Team, then request Crew
     • For complex changes or when you need extra confidence.
     • Example: Refactor affecting multiple systems.
3. Get at least one approval before merging.

Still unsure? Reach out in #jetpack-developers for guidance!

[annacmc]

This is awesome, I love it. Added one small, non-blocking, thought/question but otherwise it all works as expected and is very cool. Thank you for working on this 🙌

[annacmc]

Can we import color vars from color-studio for these themes, or would that be adding unnecessary extra dependencies?

[grzegorz-cp]

Good point. I'll add a task to check this and see how/if we can leverage CSS variables for it.

[CodeyGuyDylan]

This looks great to me!