Leverage hx-swap-oob for assets

Drupal ajax.js has this:

    // Allow Drupal to return new JavaScript and CSS files to load without
    // returning the ones already loaded.
    // @see \Drupal\Core\StackMiddleWare\AjaxPageState
    // @see \Drupal\Core\Theme\AjaxBasePageNegotiator
    // @see \Drupal\Core\Asset\LibraryDependencyResolverInterface::getMinimalRepresentativeSubset()
    // @see system_js_settings_alter()
    const pageState = drupalSettings.ajaxPageState;
    options.data['ajax_page_state[theme]'] = pageState.theme;
    options.data['ajax_page_state[theme_token]'] = pageState.theme_token;
    options.data['ajax_page_state[libraries]'] = pageState.libraries;

I think we can use hx-vals on the body tag for this:
The simplest is:

hx-vals='js:{"ajax_page_state[libraries]": drupalSettings.ajaxPageState.libraries}'

But it may be more secure to dynamically set this attribute on the body tag via JS before we load HTMX rather than introduce a JS execution path into the DOM

Since this proposal adds some of our own JS, I've made a commit to the feature branch that moves HTMX JS into a subdirectory, along with the documentation expected by d.o policy.

All tests and code checks passing

Automatically closed - issue fixed for 2 weeks with no activity.