FIR IDE: handle importing scopes in completion in HL API

Co-authored-by: Roman Golyshev <roman.golyshev@jetbrains.com>

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/scopes/KtImportingScope.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.frontend.api.scopes
+
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+interface KtImportingScope : KtScope {
+    val imports: List<Import>
+    val isDefaultImportingScope: Boolean
+}
+
+interface KtStarImportingScope : KtImportingScope {
+    override val imports: List<StarImport>
+}
+
+interface KtNonStarImportingScope : KtImportingScope {
+    override val imports: List<NonStarImport>
+}
+
+sealed class Import {
+    abstract val packageFqName: FqName
+    abstract val relativeClassName: FqName?
+    abstract val resolvedClassId: ClassId?
+}
+
+class NonStarImport(
+    override val packageFqName: FqName,
+    override val relativeClassName: FqName?,
+    override val resolvedClassId: ClassId?,
+    val callableName: Name?,
+) : Import()
+
+class StarImport(
+    override val packageFqName: FqName,
+    override val relativeClassName: FqName?,
+    override val resolvedClassId: ClassId?,
+) : Import()

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/scopes/KtScope.kt

@@ -10,6 +10,8 @@ import org.jetbrains.kotlin.idea.frontend.api.symbols.*
 import org.jetbrains.kotlin.name.Name
 
 interface KtScope : ValidityOwner {
+    // TODO check that names are accessible
+    // maybe return some kind of lazy set
     fun getAllNames(): Set<Name>
     fun getCallableNames(): Set<Name>
     fun getClassLikeSymbolNames(): Set<Name>