MAGN-1429 Need snapping in inputs

There are two defects identified in Port snapping. 
1. Ports with many outputs (especially the code block node) have different port snapping region  
2. Mouse pointer says ArcAdd, when the mouse pointer is outside snapping region.

This fix addresses both the defects. 
1. Changed the port snapping region boundaries for OUTPUT ports. 
2.  On MouseLeave (from snapping region) event, the ports are still ready for connection, and hence the cursor was showing as arc add. Now, this behavior is changed inside the function CheckActiveConnectorCompatibility . 

- [ ] @ikeough