Optimize CI by using a custom Docker container with pre-installed dependencies.

This change introduces a Docker container (`.ci/container/Dockerfile`) that pre-installs:
- OpenJDK 8 (ZuluFX), 11, 17, 21, and 25 (Zulu).
- Android SDK (command-line tools, platform-tools, build-tools) and NDK dependencies.
- Ant, Maven, Python 3.
- Codename One binaries (`cn1-binaries`).
- Required libraries for headless UI testing (xvfb, libgl1-mesa-dri, libncurses6).

Updates `pr.yml`, `ant.yml`, and `scripts-android.yml` to run jobs inside this container (`ghcr.io/codenameone/codenameone/ci-container:latest`), removing redundant setup steps (JDK download, tool installation) to improve build speed and reproducibility.

The workflow `.github/workflows/build-container.yml` is added to build and push this container image to GHCR, ensuring the image tag is always lowercase to comply with registry requirements.

Also updates `scripts/setup-workspace.sh` to respect the `CN1_BINARIES` environment variable and handle the pre-configured environment correctly.

Explicit `packages: read` permissions are added to `pr.yml`, `ant.yml`, and `scripts-android.yml` to allow pulling the CI container from GHCR. The `pr.yml` workflow now defaults to `bash` shell to support `pipefail`. The `scripts-android.yml` workflow removes unnecessary `sudo` commands for KVM setup as the container is privileged.

Author: google-labs-jules[bot]

.github/workflows/pr.yml

@@ -40,6 +40,9 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: ghcr.io/codenameone/codenameone/ci-container:latest
+    defaults:
+      run:
+        shell: bash
 
     steps:
     - uses: actions/checkout@v1

.github/workflows/scripts-android.yml

@@ -118,11 +118,6 @@ jobs:
       - name: Build Hello Codename One Android app
         id: build-android-app
         run: ./scripts/build-android-app.sh -q -DskipTests
-      - name: Enable KVM for Android emulator
-        run: |
-          echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules
-          sudo udevadm control --reload-rules
-          sudo udevadm trigger --name-match=kvm
       - name: Run Android instrumentation tests
         uses: reactivecircus/android-emulator-runner@v2
         with: