Add gitpod.io config

[IDE]

Author: lemmy

.gitpod.yml

@@ -0,0 +1,8 @@
+tasks:
+  - init: bash -i .devcontainer/install.sh
+    command: sudo ln -s /workspace /workspaces && sdk install ant
+
+vscode:
+  extensions:
+    - alygin.vscode-tlaplus-nightly
+    - vscjava.vscode-java-pack