[explorer, moves, position] Implement bespoke make_move and unmake_move methods on Position

Instead of inheriting the MakeMove and UnmakeMove traits by being a BoardProvider,
implement bespoke versions of these two methods. This gives Position a chance to
do some of its own work (tracking captures, move records, etc) when making a move.

Pass the move record by reference to the unmake_move() method. Saves a copy.

Export the Result types for MakeMove and UnmakeMove.

moves/src/make_move.rs

@@ -8,7 +8,7 @@ use chessfriend_board::{
 use chessfriend_core::{Color, Piece, Rank, Square, Wing};
 use thiserror::Error;
 
-type MakeMoveResult = Result<MoveRecord, MakeMoveError>;
+pub type MakeMoveResult = Result<MoveRecord, MakeMoveError>;
 
 #[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
 pub enum ValidateMove {