Button Block: Add draft page creation capability

[dhruvikpatel18]

Closes #56163

What?

This PR adds the ability to create draft pages directly from the button block in the navigation editor, similar to how it already works in the navigation link block.

Why?

Currently, users can create a draft page from the custom link block in the navigation editor if the page doesn't exist, but this functionality isn't available in the button block. This PR addresses this inconsistency by implementing the same feature in the button block, providing a more consistent editing experience.

How?

1. Adds draft page creation functionality to the button block's LinkControl component
2. Imports necessary components and utilities from WordPress core
3. Adds permission checks to control when the draft creation feature is available
4. Uses the same pattern already implemented in the navigation link block

Testing Instructions

1. Create a new post or page
2. Insert a navigation block
3. Add a button block to the navigation
4. Click on the link icon in the toolbar to edit the link
5. In the link search field, enter a page name that doesn't exist yet
6. Verify that an option appears to "Create draft page: [your search term]"
7. Click on this option and verify that a draft page is created and linked

Screenshots or screencast

Before

Screen.Recording.2025-02-28.at.2.21.54.PM.mov

After

Screen.Recording.2025-02-28.at.2.34.04.PM.mov

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Co-authored-by: dhruvikpatel18 <[email protected]>
Co-authored-by: ajlende <[email protected]>

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[Mamaduka]

Thanks for contributing, @dhruvikpatel18!

I think we can reduce boilerplate code here by using the same approach as the Link format. See the InlineLinkUI component for details.