Remove Gradle hacks and upgrade SDK

[blasten]

Description

Remove the embedding dependency fallback since they were added in Flutter v1.12.13. Also, bump the SDK version.

Related Issues

flutter/flutter#47153

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (flutter analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy.
• I updated CHANGELOG.md to add a description of the change.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md and increment major revision).
• No, this is not a breaking change.

[mklim]

LGTM as is modulo one nit about the versioning. If you have time for some more work there's some extra changes that are a part of flutter/flutter#47153, but I don't think you need to get those landed as part of this CL to merge it in.

• Add the embedding v2 metadata xml tag. Otherwise, we're not autogenerating the v2 plugin registration. But since the tool can only autogenerate for one version of the embedding (even if it can toggle between v1 and v2 plugin APIs against the v2 embedding), we'd have to manually register the plugin in the EmbedderV1Activity.java.
• Change to the getBinaryMessenger getter since getFlutterEngine.getDartExecutor is deprecated.
• Remove the MainActivity for the v2 embedding in the example now since it has no content.

[mklim]

nit: Should this be a patch or a minor patch bump? If you're intending for this to be a patch, all the ones that are under 1.0.0 need to have a +1 appended. If it's intended to be minor, all the ones above 1.0.0 should have the middle digit incremented. Right now it looks like the last digit is always being incremented, but with how pub handles dependencies that ends up being inconsistent.

I think it makes the most sense for this to be a patch upgrade because it's bumping a dependency (semver says that's a patch upgrade on its own) and fixing an internal issue. But I can see it going the other way.

[gaaclarke]

My thoughts exactly when looking through this. Should upgrading flutter dependency increment the patch or minor number? I don't know the answer but minor seem more right to me.

[mklim]

Yeah, I don't think there's a single right answer. Here's the semver spec on it: https://semver.org/#what-should-i-do-if-i-update-my-own-dependencies-without-changing-the-public-api. That suggests patch in most cases. Since this is the Flutter SDK itself though I can see the argument for it being a minor bump, because in a roundabout way it is part of the public API of the plugin, since everyone needs to have at least that Flutter SDK version to get the plugin version.

[blasten]

I thought about bumping the minor for the same reason you described. If there's a strong reason for bumping the patch, I can definitely do that.