chore: init monorepo with launcher and server submodules

.gitmodules

@@ -0,0 +1,8 @@
+[submodule "launcher"]
+	path = launcher
+	url = ssh://git@gitea.mrixs.me:2222/Mrixs/MrixsCraft-launcher.git
+	branch = master
+[submodule "server"]
+	path = server
+	url = ssh://git@gitea.mrixs.me:2222/Mrixs/MrixsCraft-server.git
+	branch = master