[board] Move MakeMoveBuilder::new() to an impl that specifies NoMove

I can build these now without having to specify a type for M.

board/src/position/builders/move_builder.rs

@@ -41,17 +41,19 @@ pub enum ValidatedMove {
 impl MoveToMake for NoMove {}
 impl MoveToMake for ValidatedMove {}
 
-impl<'p, M> Builder<'p, M>
-where
-    M: MoveToMake,
-{
+impl<'p> Builder<'p, NoMove> {
     pub fn new(position: &'p Position) -> Builder<'p, NoMove> {
         Builder {
             position,
             move_to_make: NoMove,
         }
     }
+}
 
+impl<'p, M> Builder<'p, M>
+where
+    M: MoveToMake,
+{
     pub fn make(self, mv: &Move) -> Result<Builder<'p, ValidatedMove>, MakeMoveError> {
         let from_square = mv.from_square();