Gutenberg - Hide undo/redo buttons in HTML Mode

[geriux]

This PR fixes an issue where the undo/redo buttons in the editor are visible when toggling to HTML mode.

These buttons don't have any functionality while editing in HTML so we should hide them and show them back if the user toggles back to the Visual mode.

To test:

• Open the app
• Open the editor
• Toggle to HTML mode by tapping on the more options (...) three dots in the right area of the navigation bar
• Expect to see the HTML editor and the undo/redo buttons to be hidden
• Toggle back to the Visual mode by tapping on the more options (...) three dots in the right area of the navigation bar
• Expect to see the undo/redo buttons in the navigation bar

Functionality
UndoRedoHTMLEditorAndroid.mov

Regression Notes

1. Potential unintended areas of impact
   It affects only the block editor

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manual testing and added UI tests

3. What automated tests I added (or what prevented me from doing so)
   I added extra steps to testUndoRedo for the EditorGutenbergTests, which includes adding a new HTMLEditorScreen.

PR submission checklist:

• I have completed the Regression Notes.
• 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.

UI Changes testing checklist:

• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• Talkback.
• 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)
• Large and small screen sizes. (Tablet and smaller phones)
• Multi-tasking: Split screen and Pop-up view. (Android 10 or higher)

[geriux]

Hey @thomashorta 👋 I've assigned you as a reviewer for this PR, I was wondering if you could please check it out? Since you are familiar with this feature 😃 Let me know if you can review it, thank you!

[wpmobilebot]

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

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr18889-976a0ca
	Commit	976a0ca
	Direct Download	wordpress-prototype-build-pr18889-976a0ca.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

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

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr18889-976a0ca
	Commit	976a0ca
	Direct Download	jetpack-prototype-build-pr18889-976a0ca.apk

Note: Google Login is not supported on these builds.

[irfano]

The feature and tests work as explained. LGTM! 👍🏻