Fixes: #2419

Related PRs:

• gutenberg: Disable Page Template picker if modal layout picker is available WordPress/gutenberg#23872
• WordPress-iOS: Create Modal Layout Picker Container for new Gutenberg pages and feature flag for development WordPress-iOS#14456

Description

This change enables the mobile editor to accept the capability modalLayoutPicker and based on that conditionally show or hide the Template Picker.

Opening this PR to generate a bundle so that the toggle in iOS is testable.

How has this been tested?

To disable or enable the development version of Modal Layout Picker

• Open the app from the build Create Modal Layout Picker Container for new Gutenberg pages and feature flag for development WordPress-iOS#14456 (comment) or a local development build
  • By default, the modal layout picker will be enabled.
  • From the site page:
    • Click on your Gravatar.
    • Click on App Settings.
    • Click on Debug.
    • Toggle "Gutenberg Modal Layout Picker" to enable or disable the picker
      To toggle:

      

On iOS using the build options mentioned above

• With Gutenberg Modal Layout Picker toggled on:

  • Select to create a new page
  • Expect to see the container for the new modal Layout Picker
  • Select "Create Blank Page"
  • Expect the current template picker to be hidden

• With Gutenberg Modal Layout Picker toggled on:

  • Select an existing page or draft without content (just a title)
  • You should not see the new Modal Layout Picker
  • Expect the current template picker to be hidden

• With Gutenberg Modal Layout Picker toggled off:

  • Select to create a new page
  • You should not see the new Modal Layout Picker
  • Expect the current template picker to be shown.

• With Gutenberg Modal Layout Picker toggled off:

  • Select an existing page or draft without content (just a title)
  • You should not see the new Modal Layout Picker
  • Expect the current template picker to be shown

• With Gutenberg Modal Layout Picker toggled on or off:

  • Select an existing page or draft with content
  • Expect the current template picker to be hidden

On Android running a metro server or generating a build

• Existing Blank Page
  • Select an existing page or draft without content (just a title)
  • Expect the current template picker to be shown
• New Page
  • Select to create a new page
  • Expect the current template picker to be shown.
• Existing Page
  • Select an existing page or draft with content
  • Expect the current template picker to be hidden

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes more info and have added them to [RELEASE-NOTES.txt](RELEASE-NOTES.txt) if necessary.