chore: add .devcontainer configuration from cargo-near-new-project-template

Author: dj8yf0μl

.devcontainer/devcontainer.json

@@ -0,0 +1,8 @@
+{
+  "name": "NEAR Devcontainer Rust",
+
+  "image": "ghcr.io/near/near-devcontainer:latest",
+
+  // Uncomment and modify the following lines if necessary
+  // "forwardPorts": [8000],
+}