[Android] Refactor Intent-driven engine flags into a variant-specific module - #191924

…flags (#13931)

_Description of what this PR is changing or adding, and why:_
Adds some corrections +renames to a breaking change page on restricting
engine config flags for Android.

_Issues fixed by this PR (if any):_
Part of flutter/flutter#190461

_PRs or commits this PR depends on (if any):_
flutter/flutter#191924 (but this can land at any
time)

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

… module (flutter#191924)

Configures the Android embedding to ignore engine configuration flags
set via `Intent` in release mode. All flag parsing from `Intent`s is
also stripped from release engine binaries as an additional security
measure. Also adds an integration test to ensure flags set via `Intent`
are ignored for apps running in release mode.

As part of this implementation, deprecates the internal interface method
`FlutterActivityAndFragmentDelegate.Host.getFlutterShellArgs` which is
to be replaced
by`FlutterActivityAndFragmentDelegate.Host.getFlutterEngineFlags`. After
a stable release, `getFlutterShellArgs` will be removed:
flutter#193256. **This is not a
breaking change; developers cannot override this interface.** They can
only subclass `FlutterActivity` and `FlutterFragment` and call
`getFlutterShellArgs` which will still work as intended with a
deprecation notice.

Fixes flutter#190461.

Related issue: While working on this, I thought it would be good to
track adding the ability to negate all flags because currently,
presence-only boolean flags (like `--trace-startup`) cannot have their
setting in the manifest negated by the command line, which is
counter-intuitive: flutter#193354

Related PR: Made some updates to the breaking change page for this
project for flutter/website#13931 (directly
related to my `Flutter-Android-Engine-Flags.md‎` updates)

(@camsim99 authored description)

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [AI contribution guidelines] and understand my
responsibilities, or I am not using AI tools.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

---------

Co-authored-by: Camille Simon <[email protected]>
Co-authored-by: Camille Simon <[email protected]>