[debug] Breakpoints set on the wrong line number when there is a closure field after a constructor

Attempting to set a breakpoint on the 'print 8' line will instead set the breakpoint on 'print 9'.

public class Printing {
	Printing() {
		print 8
	}
	def x = {
		print 9
	}
}

This is because of the way that Groovy rearranges field initializer nodes to be placed in a constructor.

In ValidBreakpointLocationFinder, for constructors and <clinit>, we need to change the ordering of statements being processed. Need to look at the RHS of an assignment if the assignment has no sloc and order by the RHS line number.