Refactor Shorebird CLI to support configurable URLs and improve test coverage

- Updated AAR releaser test to use ShorebirdProcess.defaultFlutterStorageBaseUrl.
- Changed macOS releaser test to reference a new troubleshooting URL.
- Enhanced shorebird_yaml_test with deserialization for AOT patch metadata.
- Modified network_checker_test to check self-hosted URLs from ShorebirdEnv.
- Added tests for artifact paths in shorebird_artifacts_test.
- Updated shorebird_cli_command_runner_test to reflect new repository URL.
- Improved shorebird_env_test with additional tests for shorebirdRoot and engine revision fallback.
- Adjusted shorebird_flutter_test to use environment variables for Flutter Git URL.
- Updated shorebird_process_test to utilize default Flutter storage URL.
- Enhanced shorebird_validator_test to link to the default hosted URL.
- Updated shorebird_web_console_test to use the configured hosted URL.
- Refactored code_push_client to use default hosted URL for API requests.
- Updated README and generation scripts for the code_push_protocol package to reflect new OpenAPI spec source.
- Modified shared.sh to allow configurable Flutter repository and storage URLs.

Signed-off-by: Tony <tonylu@tony-cloud.com>

third_party/flutter/bin/internal/shared.sh

@@ -8,19 +8,23 @@ set -e
 # Needed because if it is set, cd may print the path it changed to.
 unset CDPATH
 
-# Either clones or pulls the Shorebird Flutter repository, depending on whether FLUTTER_PATH exists.
+# Either clones or pulls the configured Flutter repository, depending on
+# whether FLUTTER_PATH exists.
 function update_flutter {
+  local flutter_git_url="${SHOREBIRD_FLUTTER_GIT_URL:-https://git.tonycloud.org/flutter/flutter.git}"
+  local flutter_storage_base_url="${SHOREBIRD_FLUTTER_STORAGE_BASE_URL:-${FLUTTER_STORAGE_BASE_URL:-http://localhost:8080/download.flutter.io}}"
+
   if [[ -d "$FLUTTER_PATH" ]]; then
     git -C "$FLUTTER_PATH" fetch
   else
-    git clone --filter=tree:0 https://github.com/shorebirdtech/flutter.git --no-checkout "$FLUTTER_PATH"
+    git clone --filter=tree:0 "$flutter_git_url" --no-checkout "$FLUTTER_PATH"
   fi
   # -c to avoid printing a warning about being in a detached head state.
   git -C "$FLUTTER_PATH" -c advice.detachedHead=false checkout "$FLUTTER_VERSION"
   SHOREBIRD_ENGINE_VERSION=`cat "$FLUTTER_PATH/bin/internal/engine.version"`
   echo "Shorebird Engine • revision $SHOREBIRD_ENGINE_VERSION"
-  # Install Shorebird Flutter Artifacts
-  FLUTTER_STORAGE_BASE_URL=https://download.shorebird.dev $FLUTTER_PATH/bin/flutter --version
+  # Install Flutter artifacts through the configured open mirror.
+  FLUTTER_STORAGE_BASE_URL="$flutter_storage_base_url" "$FLUTTER_PATH/bin/flutter" --version
 }
 
 function pub_get_with_retry {