Unresolved reference: kotlinx

When trying KotlinLanguageServer with Android projects that use the [Kotlin Android extensions](https://kotlinlang.org/docs/tutorials/android-plugin.html), Kotlin LSP returns an error saying "kotlinx" can not be resolved.

This happens both with Gradle DSL and Gradle Kotlin DSL. I also tried shuffling the 'dependency' of the android-extensions from the root project to the module build.gradle but to no success.

Specifically it's failing on `import kotlinx.android.synthetic.main.activity_main.*`

A `gradle build` succeeds with no issues, so this seems to be a problem with KotlinLanguageServer specifically.

Reproduce the failure in an Android project using the referenced `import kotlinx.android.synthetic.main.activity_main.*` and compare it with the successful `gradle build`. Inspect how KotlinLanguageServer resolves dependencies for both Gradle DSL and Gradle Kotlin DSL; done means the import resolves without errors in the language server.

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