Fix several false positives and make safer "redundant companion ref"

Don't report it on an import directive #KT-23520 Fixed
Don't report it if companion nested class is referenced #KT-23519 Fixed
Check companion reference both by descriptor and by name

idea/testData/inspectionsLocal/redundantCompanionReference/companionDoubleNested.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+
+class Owner {
+    companion object {
+        class InCompanion {
+            class Nested
+        }
+    }
+}
+
+val y = Owner.<caret>Companion.InCompanion.Nested()

idea/testData/inspectionsLocal/redundantCompanionReference/companionNested.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+class Owner {
+    companion object {
+        class InCompanion
+    }
+}
+
+val y = Owner.<caret>Companion.InCompanion()

idea/testData/inspectionsLocal/redundantCompanionReference/import.kt

@@ -0,0 +1,13 @@
+// PROBLEM: none
+
+import Owner.<caret>Companion.some
+
+class Owner {
+    companion object {
+        const val some = ""
+    }
+}
+
+class User {
+    val anything = some
+}

idea/testData/inspectionsLocal/redundantCompanionReference/named.kt

@@ -0,0 +1,9 @@
+class C {
+    companion object Obj {
+        fun create() = C()
+    }
+}
+
+fun test() {
+    C.<caret>Obj.create()
+}

idea/testData/inspectionsLocal/redundantCompanionReference/named.kt.after

@@ -0,0 +1,9 @@
+class C {
+    companion object Obj {
+        fun create() = C()
+    }
+}
+
+fun test() {
+    C.create()
+}