fix($animate): insert elements at the start of the parent container instead of at the end

BREAKING CHANGE: $animate will no longer place elements at the end of the parent container
when enter or move is used with a parent container element. Any former directives that rely
on this feature must be slightly modified to work around this fix. The same effect can be achieved
by finding the final element in the parent container list and using that as the after element
(which is the 3rd argument in the enter and move $animate operations).

Closes #4934