Customizer preview fails to persist state query params through history.pushState() calls

[westonruter]

There is a typo in [38810] for #30937 where the injectUrlWithState method fails to return the new state URL that is mutated. It is capturing the state data but it is not ensuring the URL gets the state params.

Also, if the history.pushState() or history.replaceState() call is done before the preview-ready event triggers, then a JS error is likely to result because wp.customize.settings would not be defined yet. It is unnecessary to define anyway because the query params are in the URL to begin with anyway.

[westonruter]

In 39060:

Customize: Ensure state query params persist in preview through calls to history.pushState() & history.replaceState().

Allow history to be manipulated before DOM ready by sourcing state params from the current URL instead of from the wp.customize.settings object, since they will be the same anyway. This fixes a JS error since wp.customize.settings is not defined before DOM ready.

Amends [38810].
See #30937.
Fixes #38592.