Fixes #5587 - Makes profile edit form and user settings sticky

By mistake I've made user settings sticky as well ;-)

I'd like to add here info on top of the form: "This form has unsaved changes". It could be kind of dedicated function/view that takes form name, checks if we have sticky values in session (`elgg_is_sticky_form`) and if yes, displays warning. It makes sense for forms that modify existing data, as values being read from session are not apparent.

It looks 1.9-ish to me though.