Support for import aliases in code completion

#KT-8848 Fixed

idea/idea-completion/testData/basic/java/importAliases/ExtensionValSmart.kt

@@ -0,0 +1,9 @@
+import java.io.File
+import kotlin.io.extension as ext
+
+fun foo(file: File): String {
+    return file.ex<caret>
+}
+
+// COMPLETION_TYPE: SMART
+// EXIST: { lookupString: "ext", itemText: "ext", tailText: " for File (kotlin.io.extension)" }