Add Support for Appearance Tools

[danielwrobert]

This provides support for spacing, border, typography, and color options, even without using theme.json.

Properties that should be added to various block settings are:

• Border
• Color
• Dimensions
• Position
• Spacing
• Typography

Additional references:

• https://wordpress.org/documentation/wordpress-version/version-6-5/#add-appearance-tools-to-classic-themes
• https://developer.wordpress.org/themes/global-settings-and-styles/settings/appearance-tools/

Screenshots

Image Block

Before	After

Text Block

Before	After

Layout Block

Before	After

How to test the changes in this Pull Request:

1. Insert an Image block in the editor and confirm that the sidebar settings have an additional tab added for Styles (see the After screenshot under Image Block above). Confirm changes to the new settings are reflected in the editor and on the front end.
2. Insert a text block (Heading, Paragraph, etc) in the editor and confirm the Dimensions section added to the sidebar settings (see the After screenshot under Text Block above). This should allow additional spacing options (namely Margin). Confirm changes to the new settings are reflected in the editor and on the front end.
3. Insert a layout block (Row or Column) in the editor and confirm added controls under the Styles tab in the sidebar settings(see the After screenshot under Layout Block above). Confirm changes to the new settings are reflected in the editor and on the front end.
4. Smoke test additional Core blocks to ensure the new properties are added where expected and do not have any unintended side-effects.

Changelog

Add – support for Appearance Tools in Classic themes. #2143

[danielwrobert]

The change tests well and looks good to me. Just wondering if the languages/storefront.pot file update is needed?

Good point. While we're tracking it and should keep it up to date, it doesn't need to be included here.

I've removed that commit from this PR.

I also rebased with trunk and I see @gigitux already updated the POT file today so we're all set there!