Add build option to force inclusion of dev_dependencies - #171445

In the latest stable release version of Flutter dev_dependencies are excluded from release builds. This leads to the issues #170119 and #167377. The PR #171015 fixed this issues only for iOS and macOS build by going a step backward. The PR changed the behavior to always include the dev_dependencies even in release build. This has the downside that the release build gets bigger again and maybe it could lead to other problems as well. So, in general it is desireable to strip out the dev_dependencies in release builds. However, there are scenarios like integration testing in which you want to have a release build including dev_dependencies.

So my PR adds the build option --force-include-dev-dependencies that ensures that the dev_dependencies are included in all build modes.

I would prefer this PR over #171015 because it does not go a step backward and solves the same issues. This PR is not a breaking change.

Example usage:

flutter build ios integration_test/foo_test.dart --release --force-include-dev-dependencies

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• I followed the breaking change policy and added Data Driven Fixes where supported.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.