Status: Add is_p2_site and get_wpcom_site_id helper functions to Status package

[coder-karen]

Resolves VULCAN-250

Proposed changes:

• This PR adds an is_p2_site and a get_wpcom_site_id helper function to the Status\Host package.
• These will be used to replace multiple checks throughout the monorepo in a later PR.
• This PR also adds additional tests for the new functions

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:

• The functions are not in use, so code review is all that is needed.

[github-actions]

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 WoA dev 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 (Jetpack or WordPress.com Site Helper), and enable the update/status-package-add-p2-helper branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack update/status-package-add-p2-helper

bin/jetpack-downloader test jetpack-mu-wpcom-plugin update/status-package-add-p2-helper

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

[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 Review, ...).
  
• ✅ Add a "[Type]" label (Bug, Enhancement, Janitorial, Task).
  
• ✅ Add testing instructions.
  
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• ✅ 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 🤖

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/status/src/class-host.php	22/57 (38.60%)	3.18%	4 💔

Full summary · PHP report · JS report

_{Coverage check overridden by Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code .}