feat: GutenbergKit code editor

[dcalhoun]

Related:

• https://github.com/Automattic/dotcom-forge/issues/10117
• feat: Toggle code editor GutenbergKit#60
• feat: GutenbergKit code editor WordPress-Android#21582

To test: See wordpress-mobile/GutenbergKit#60.

Regression Notes

1. Potential unintended areas of impact
   Regressions within Aztec and Gutenberg Mobile.
2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manually tested the editors.
3. What automated tests I added (or what prevented me from doing so)
   Deemed unnecessary for the experimental editor.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Testing checklist:

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[dangermattic]

	2 Warnings
⚠️	Modules/Package.swift was changed without updating its corresponding Package.resolved. Please resolve the Swift packages as appropriate to your project setup (e.g. in Xcode or by running swift package resolve).
⚠️	PR is not assigned to a milestone.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack Alpha by scanning the QR code below to install the corresponding build.

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23979-9f9925c
	Version	25.6
	Bundle ID	com.jetpack.alpha
	Commit	9f9925c
	App Center Build	jetpack-installable-builds #10390

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23979-9f9925c
	Version	25.6
	Bundle ID	org.wordpress.alpha
	Commit	9f9925c
	App Center Build	WPiOS - One-Offs #11359

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.