[board] Rename the moves modules → move_generator

Update the imports.
Also update some references to crate symbols in move_generator macros to use $crate.

board/src/moves/move_set.rs

@@ -1,68 +0,0 @@
-use crate::{piece::PlacedPiece, BitBoard, Move};
-
-struct BitBoardSet {
-    quiet: BitBoard,
-    captures: BitBoard,
-}
-
-struct MoveListSet {
-    quiet: Vec<Move>,
-    captures: Vec<Move>,
-}
-
-/// A set of moves for a piece on the board.
-pub(super) struct MoveSet {
-    piece: PlacedPiece,
-    bitboards: BitBoardSet,
-    move_lists: MoveListSet,
-}
-
-impl MoveSet {
-    pub(super) fn new(piece: PlacedPiece) -> MoveSet {
-        MoveSet {
-            piece,
-            bitboards: BitBoardSet {
-                quiet: BitBoard::empty(),
-                captures: BitBoard::empty(),
-            },
-            move_lists: MoveListSet {
-                quiet: Vec::new(),
-                captures: Vec::new(),
-            },
-        }
-    }
-
-    pub(super) fn quiet_moves(
-        mut self,
-        bitboard: BitBoard,
-        move_list: impl Iterator<Item = Move>,
-    ) -> MoveSet {
-        self.bitboards.quiet = bitboard;
-        self.move_lists.quiet = move_list.collect();
-
-        self
-    }
-
-    pub(super) fn capture_moves(
-        mut self,
-        bitboard: BitBoard,
-        move_list: impl Iterator<Item = Move>,
-    ) -> MoveSet {
-        self.bitboards.captures = bitboard;
-        self.move_lists.captures = move_list.collect();
-
-        self
-    }
-
-    /// Return a BitBoard representing all possible moves.
-    pub(super) fn bitboard(&self) -> BitBoard {
-        self.bitboards.captures | self.bitboards.quiet
-    }
-
-    pub(super) fn moves(&self) -> impl Iterator<Item = &Move> {
-        self.move_lists
-            .captures
-            .iter()
-            .chain(self.move_lists.quiet.iter())
-    }
-}