Disable custom layout width in global styles

[unscripted]

Changes proposed in this pull request

This PR adds the settings.layout.allowCustomContentAndWideSize property to the theme.json file to disable the editor's custom content and wide size inputs. This will maintain design system consistency and simplify the content editing experience.

It will also ensure that all content follows predefined width constraints, reducing layout inconsistencies and improving the overall user experience.

Before	After

Testing

How to test the changes in this pull request

Follow the steps below to test the changes in this PR.

1. Open this branch in a local environment.
2. Navigate to a page in the admin.
3. Add a group block.

Functional tests

As the functional tester for this pull request, I verify that:

• It does not have the content width or wide width inputs in the Layout panel.

[EugeneKyale]

This works as expected.

[sstruemph]

@unscripted This is feature is used often on a individual block basis to create "skinny" content that is less than the default content width. At first content editors were using padding to do this and that creates issues on mobile.

Since this is used so often, I think we should keep this feature enabled.