[Android] Restrict engine flags via Intent extras to non-release modes #190461

In #180686, we targeted complete removal of the ability to set engine flags via Intent extras to secure applications from dynamic parameter injection vectors (like spoofing --aot-shared-library-name for example). However, eliminating this pathway entirely breaks hermetic build systems and critical local testing workflows where developers deploy prebuilt binaries and dynamically modify flags via command line. Because the Android OS intentionally lowers security sandboxing for debuggable builds anyway, blocking local Intent flags in debug/profile environments does not provide real-world security.

Instead, we will establish a build-mode-specific trust boundary: Release builds will treat production application boundaries as immutable and ignore/strip engine shell flag parsing from Intent extras, while debug and profile builds will prioritize velocity and preserve the ability to accept engine shell arguments via Intent.

Task list for implementing the restriction:

• Update the CLI to inject engine configuration flags into the manifest during Gradle compilation for release builds
• Implement a fatal CLI check when developers attempt to run a prebuilt release APK with command line engine flags (those flags will now be ignored)
• Completely strip engine flag parsing from Intent extras in release builds (only retaining the logic in debug and profile modes)
• Document the Flutter CLI's new behavior and provide migration guidelines for non-Gradle users to declare flags statically in their release manifests pre-compilation

After this is complete, FlutterShellArgs should be deleted after one stable release with the changes: #193256