ci: prebuild dev containers

Fixes #2181

Add a GitHub Actions workflow to prebuild dev containers and update devcontainer configuration.

* **Add GitHub Actions workflow**: Create `.github/workflows/prebuild-devcontainers.yml` to schedule and trigger builds for the dev container image.
* **Add devcontainer configuration**: Create `.devcontainer/devcontainer.jso` to specify the image to be used for the dev container.

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/dashpay/platform/issues/2181?shareId=XXXX-XXXX-XXXX-XXXX).

.devcontainer/devcontainer.jso

@@ -0,0 +1,4 @@
+{
+  "name": "Dash Platform Dev Container",
+  "image": "ghcr.io/dashpay/platform/devcontainer"
+}

.github/workflows/prebuild-devcontainers.yml

@@ -0,0 +1,40 @@
+name: Prebuild Dev Containers
+
+on:
+  schedule:
+    - cron: "0 0 * * *"
+  push:
+    paths:
+      - '.devcontainer/**'
+      - '.github/workflows/prebuild-devcontainers.yml'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v3
+
+      - name: Set up QEMU for multi-architecture builds
+        uses: docker/setup-qemu-action@v3
+
+      - name: Setup Docker buildx for multi-architecture builds
+        uses: docker/setup-buildx-action@v3
+        with:
+          use: true
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ghcr.io
+          username: dashpay
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Platform devcontainer
+        uses: devcontainers/[email protected]
+        with:
+          imageName: ghcr.io/dashpay/platform/devcontainer
+          platform: linux/amd64,linux/arm64
+          configFile: .devcontainer/build.json
+          push: true
+          cacheFrom: ghcr.io/dashpay/platform/devcontainer