Add devcontainer configuration (#62)

.devcontainer/devcontainer.json

@@ -0,0 +1,36 @@
+{
+  "name": "ESPHome Home Assistant add-on devcontainer",
+  "image": "ghcr.io/esphome/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"
+  ],
+  "mounts": [
+    "type=volume,target=/var/lib/docker"
+  ],
+  "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
+  }
+}