Removing the sslseal option, setting, and frontend display.

[kimcoleman]

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Changes proposed in this Pull Request:

Removes the SSL Seal Code setting and deletes the option on upgrade. Sites should instead leverage a hook in the checkout page. Future versions may allow for more modular checkout form building that will support block editor or shortcodes and inserting via the post editor.

Other information:

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Changelog entry

• DEPRECATED: Removed setting and display of SSL Seal Code option from database and frontend pages.

[kimcoleman]

@dparker1005 Merge conflicts are fixed on this one.