Add DevContainer, VSCode config and extensions.json

(cherry picked from commit 5061dc4b5e5ea9925740496a5939a1762788b793)

Closes #3414

.devcontainer/devcontainer.json

@@ -0,0 +1,19 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/dotnet
+{
+  "name": "Readarr",
+  "image": "mcr.microsoft.com/devcontainers/dotnet:1-6.0",
+  "features": {
+    "ghcr.io/devcontainers/features/node:1": {
+      "nodeGypDependencies": true,
+      "version": "16",
+      "nvmVersion": "latest"
+    }
+  },
+  "forwardPorts": [8787],
+  "customizations": {
+    "vscode": {
+      "extensions": ["esbenp.prettier-vscode"]
+    }
+  }
+}