Using the `focus` event on the permalink custom structure field made impossible
to navigate through all the form fields using only the keyboard without actually
selecting the custom structure setting. Instead, using click and input preserves
the original functionality when using any kind of pointing or input device.
Also changes `attr()` to `prop()` as recommended for a `checked` property.
Props afercia.
Fixes#40982.
Merges [40897] to the 4.8 branch.
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