Fix unused import inspection for scripts not under source roots (including build.gradle.kts and scratches)

KT-20040 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt

@@ -61,7 +61,7 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
     companion object {
         fun analyzeImports(file: KtFile): ImportData? {
             if (file is KtCodeFragment) return null
-            if (!ProjectRootsUtil.isInProjectSource(file)) return null
+            if (!ProjectRootsUtil.isInProjectSource(file, true)) return null
             if (file.importDirectives.isEmpty()) return null
 
             val optimizerData = KotlinImportOptimizer.collectDescriptorsToImport(file)