hx-history not working on partial content

When using `hx-push-url` with partial content, pressing the back button does not actually work.

From looking at the code, it seems that it's related to the context being on the body.
In the case where we do not actually control the body, the history aspect fails completely.
I have been digging and it seems there is a case where HTMX is loaded dynamically on page load where the DOMContentLoaded is never triggered.

If I instead push the events for the ready function into an array, and then manually call those functions, everything works perfectly.
https://github.com/bigskysoftware/htmx/blob/10e8656af500d8dc3bba54459b8f29d53f326471/src/htmx.js#L4994-L5014

So, we need to find a way to reliably trigger that event... I'll keep looking and update this accordingly.