Attempt to reland #142008 half a year later.
Benefit: this will be the first plugin in Flutter repo that uses Gradle KTS for Android buildscripts. Once it works fine, we can follow up with migration of more plugins later.
[The previous error message](https://github.com/flutter/flutter/pull/142008#issuecomment-1939558432) was:
```
e: /b/s/w/ir/cache/gradle/caches/jars-8/42139b5be0c79e133a7b5c5c5d5bf731/gradle-7.3.1.jar!/com/android/build/gradle/LibraryExtension.class: Class 'com/android/build/gradle/LibraryExtension' was compiled with an incompatible version of Kotlin. The binary version of its bytecode is unknown, expected version is 1.0.3
e: /b/s/w/ir/cache/gradle/caches/jars-8/043c0d54e2c1bb39208ec4477607cdf5/gradle-api-7.3.1.jar!/com/android/build/api/dsl/LibraryVariantDimension.class: Class 'com/android/build/api/dsl/LibraryVariantDimension' was compiled with an incompatible version of Kotlin. The binary version of its bytecode is unknown, expected version is 1.0.3
FAILURE: Build failed with an exception.
* Where:
Build file '/b/s/w/ir/x/w/flutter/packages/integration_test/android/build.gradle.kts' line: 36
* What went wrong:
com.android.build.gradle.LibraryExtension.setNamespace(Ljava/lang/String;)V
```
The `integration_test` plugin now puts `com.android.tools.build:gradle:8.1.0` on its classpath since https://github.com/flutter/flutter/issues/153795.
This makes me take an optimistic bet that it won't kill the autoroller now ð¤
We already have a simple app in this repo that fully uses Gradle Kotlin DSL (see #141541). The next small step is to have at least one plugin that also uses Gradle Kotlin DSL. Let's use `integration_test` for that, since it's versioned with Flutter SDK.