[K/N] Convert StubGenerator build script to Kotlin

Besides usual pros of kts, it simplifies potential reuse
of code from other build.gradle.kts (namely, Interop:Indexer).

Also, this commit fixes red code in IDE by adding proper dependencies.

kotlin-native/utilities/cli-runner/build.gradle

@@ -23,4 +23,5 @@ dependencies {
     implementation project(':kotlin-native:Interop:StubGenerator')
     implementation project(':kotlin-native:klib')
     implementation project(":kotlin-native:utilities:basic-utils")
+    implementation project(":kotlin-native-shared")
 }