KT-4794: Added functionality to KT-4574: Split If. Intention is now offered inside IF keyword

This intention adds functionality to the current Split If Intention. It is now applicable anywhere inside the <code>if</code> statement.
If at all possible can I get Pavel Talanov as my code reviewer? He reviewed the first part of this intention and created this task. 
Relates to KT-4574
Thanks in advance.