Add devcontainer (#19)

.devcontainer/devcontainer.json

@@ -0,0 +1,23 @@
+{
+  "name": "Example Home Assistant add-on repository",
+  "image": "ghcr.io/home-assistant/devcontainer:addons",
+  "appPort": ["7123:8123", "7357:4357"],
+  "postStartCommand": "bash devcontainer_bootstrap",
+  "runArgs": ["-e", "GIT_EDITOR=code --wait", "--privileged"],
+  "containerEnv": {
+    "WORKSPACE_DIRECTORY": "${containerWorkspaceFolder}"
+  },
+  "extensions": ["timonwong.shellcheck", "esbenp.prettier-vscode"],
+  "settings": {
+    "terminal.integrated.profiles.linux": {
+      "zsh": {
+        "path": "/usr/bin/zsh"
+      }
+    },
+    "terminal.integrated.defaultProfile.linux": "zsh",
+    "editor.formatOnPaste": false,
+    "editor.formatOnSave": true,
+    "editor.formatOnType": true,
+    "files.trimTrailingWhitespace": true
+  }
+}