Add entity.get_mut function

src/entity.zig

@@ -279,7 +279,14 @@ pub fn Entity(comptime ctx: anytype) type {
 
         pub fn get(self: Self, comptime T: type) ?*const T {
             const id = Lookup(ctx, T).id;
-            return @alignCast(@ptrCast(c.ecs_get_id(self.world.raw, self.raw, id)));
+            const ptr = c.ecs_get_id(self.world.raw, self.raw, id);
+            return @alignCast(@ptrCast(ptr));
+        }
+
+        pub fn get_mut(self: Self, comptime T: type) ?*T {
+            const id = Lookup(ctx, T).id;
+            const ptr = c.ecs_get_mut_id(self.world.raw, self.raw, id);
+            return @alignCast(@ptrCast(ptr));
         }
 
         pub fn set(self: Self, comptime T: type, value: T) void {