Updated mobile footer bar to hide when viewport not at top of screen, added infinity trigger to form submit logic & added a form include file for later use.

Overwritten Manuel's previous mobile footer changes as requested by Team US to make mobile footer hide completely when you move away from the top of the page (As opposed to before when the bar would hide when you clicked on a form input field).

Additionally added an Infinity trigger to the form submit logic and set a 150ms delay on form submission to give this trigger time to fire. Added an include file for the form for when we set up the form as a global include.