Unused import: support also imports as alias

#KT-12392 Fixed

idea/testData/inspections/unusedImport/file.kt

@@ -7,11 +7,12 @@ import java.util.ArrayList // used
 import java.unresolved.* // unused but unresolved
 import java.net.Unresolved // unused but unresolved
 
-import java.net.ConnectException as CE // highlighting of unused aliases not implemented yet
+import java.net.ConnectException as CE // unused
+import java.net.ConnectException as ConExc // used
 
 import RootPackageClass // unused because it's in the current package
 
-fun foo(list: ArrayList<String>, p: RootPackageClass) {
+fun foo(list: ArrayList<String>, p: RootPackageClass, e: ConExc) {
     list.add("")
     Date()
 }

idea/testData/inspections/unusedImport/inspectionData/expected.xml

@@ -17,6 +17,15 @@
         <description>Unused import directive</description>
     </problem>
 
+    <problem>
+        <file>file.kt</file>
+        <line>10</line>
+        <module>light_idea_test_case</module>
+        <entry_point TYPE="file" FQNAME="simple.kt" />
+        <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused import directive</problem_class>
+        <description>Unused import directive</description>
+    </problem>
+
     <problem>
         <file>fileInPack1.kt</file>
         <line>3</line>