BP Nouveau JS: Maybe move "bp_ajax_request" event to fadeIn complete function.

[dcavins]

As is, the very useful bp_ajax_request js event fires before the element it is referring to is fully faded in, which causes problems in some cases (like drawing new elements via js, because the elemtent isn't full size until the fadeIn is completed).

I'm attaching a patch that moves the event to the optional completed method of the fadeIn function.

However, I can imagine that soemtimes you might want to be alerted that the request has finished before the element has completely faded in, so it might be better to add a new event, like `'bp_ajax_request_fade_in_complete' rather than moving the existing event.

I'm not sure. Anyway, thanks for your consideration.

[dcavins]

Moves bp_ajax_request to fadeIn complete in Nouveau.

[imath]

Looks good to me! Thanks a lot for this improvement @dcavins 👍

[dcavins]

In 12447:

Nouveau: Change AJAX template loading event emission timing.

In Nouveau, a useful event, bp_ajax_request, is emitted when a template
is updated wth new content. However, the new content is eased in using
a fadeIn transition. This changeset moves the event to the fadeIn complete
so that any actions tied to bp_ajax_request will be operating on
visible and full-size elements.

Fixes #8128.