add defaultgamemode

src/command/defaultgamemode.rs

@@ -0,0 +1,17 @@
+#[derive(Default)]
+pub struct DefaultGamemodeCommand {
+    gamemode: Option<super::Gamemode>
+}
+
+impl DefaultGamemodeCommand {
+    pub fn gamemode(mut self, gamemode: super::Gamemode) -> Self {
+        self.gamemode = Some(gamemode);
+        self
+    }
+
+    pub fn build(self) -> super::Command {
+        let gamemode = self.gamemode.unwrap_or(super::Gamemode::Survival);
+        let s = format!("defaultgamemode {gamemode}");
+        super::Command(s)
+    }
+}