erdi/ktlint-assign-bug

Reproducer sample for pinterest/ktlint#2343

1. Clone the project.
2. Run ./gradlew :compileKotlin and see it succeed.
3. Run ./gradlew :ktlintCheck and see it fail with:

> Task :ktlintMainSourceSetCheck FAILED
<path-to-project>/src/main/kotlin/com/github/erdi/ktlint/bug/ExamplePlugin.kt:5:1 Unused import

4. Remove import org.gradle.kotlin.dsl.assign line from <path-to-project>/src/main/kotlin/com/github/erdi/ktlint/bug/ExamplePlugin.kt:5
5. Run ./gradlew :ktlintCheck and see it pass.
6. Run ./gradlew :compileKotlin and see it fail with:

e: file:///<path-to-project>/src/main/kotlin/com/github/erdi/ktlint/bug/ExamplePlugin.kt:11:9 Val cannot be reassigned