Add support for AGP 8.4

[emersion]

Fixes the following errors with AGP 8.4:

A problem occurred configuring project ':webcrypto'.
> [CXX1110] Platform version 16 is unsupported by this NDK. Please change minSdk to at least 21 to avoid undefined behavior. To suppress this error, add android.ndk.suppressMinSdkVersionError=21 to the project's gradle.properties or set android.experimentalProperties["android.ndk.suppressMinSdkVersionError"]=21 in the Gradle build file.

and

Execution failed for task ':webcrypto:processReleaseManifest'.
> A failure occurred while executing com.android.build.gradle.tasks.ProcessLibraryManifest$ProcessLibWorkAction
   > Incorrect package="com.example.webcrypto" found in source AndroidManifest.xml: /home/simon/src/webcrypto.dart/android/src/main/AndroidManifest.xml.
     Setting the namespace via the package attribute in the source AndroidManifest.xml is no longer supported.
     Recommendation: remove package="com.example.webcrypto" from the source AndroidManifest.xml: /home/simon/src/webcrypto.dart/android/src/main/AndroidManifest.xml.

[jonasfj]

Do I understand it correctly that this will drop support for Android 4.x, which is more than 12 years old at this point.

That might be acceptable, I'm guessing :D

[jonasfj]

Hmm, I'm guessing we should also look at:
https://docs.flutter.dev/release/breaking-changes/flutter-gradle-plugin-apply

I'll file it separately, as #124

[jonasfj]

Is there some kind of testing we should do to be more confident this is correct?

I'd love to have it covered in CI.

[jonasfj]

Dumb question, but do we not need this anymore?

Will minSdkVersion 21 make AGP < 4.2 irrelevant?

[emersion]

AGP 8.4 rejects AndroidManifest.xml files with a package attribute. If we only set the namespace for AGP ≥ 4.2, then on AGP < 4.2 we won't define any namespace at all and the build will fail anyways.

I think it's reasonable to ask library users to upgrade AGP ≥ 4.2 when upgrading webcrypto.dart.

[HamdaanAliQuatil]

Fixes the following errors with AGP 8.4:

A problem occurred configuring project ':webcrypto'.
> [CXX1110] Platform version 16 is unsupported by this NDK. Please change minSdk to at least 21 to avoid undefined behavior. To suppress this error, add android.ndk.suppressMinSdkVersionError=21 to the project's gradle.properties or set android.experimentalProperties["android.ndk.suppressMinSdkVersionError"]=21 in the Gradle build file.

and

Execution failed for task ':webcrypto:processReleaseManifest'.
> A failure occurred while executing com.android.build.gradle.tasks.ProcessLibraryManifest$ProcessLibWorkAction
   > Incorrect package="com.example.webcrypto" found in source AndroidManifest.xml: /home/simon/src/webcrypto.dart/android/src/main/AndroidManifest.xml.
     Setting the namespace via the package attribute in the source AndroidManifest.xml is no longer supported.
     Recommendation: remove package="com.example.webcrypto" from the source AndroidManifest.xml: /home/simon/src/webcrypto.dart/android/src/main/AndroidManifest.xml.

@emersion can you please let me know how to reproduce this error

[emersion]

Do I understand it correctly that this will drop support for Android 4.x, which is more than 12 years old at this point.

Correct. Note that the latest version of Flutter requires Android ≥ 5.x, so this just aligns the plugin requirements with Flutter's.

Hmm, I'm guessing we should also look at:
https://docs.flutter.dev/release/breaking-changes/flutter-gradle-plugin-apply

Yes, that would be nice to fix as well. But it's orthogonal.

Is there some kind of testing we should do to be more confident this is correct?

I'd love to have it covered in CI.

I've pushed a commit to upgrade the example to AGP 8.4. The failures reported in the first two commits can be reproduced there.