Lift return out: do not report for zero returns

Also, do not highlight (but suggest fix) for exactly one return
Related to KT-14900

idea/testData/inspectionsLocal/liftOut/whenToReturn/insideLoop.kt

@@ -1,3 +1,5 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
 fun foo(): Int {
     loop@ while (true) {
         <caret>when (1) {

idea/testData/inspectionsLocal/liftOut/whenToReturn/insideLoop.kt.after

@@ -1,3 +1,5 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
 fun foo(): Int {
     loop@ while (true) {
         return when (1) {

idea/testData/inspectionsLocal/liftOut/whenToReturn/whenOneReturn.kt

@@ -0,0 +1,8 @@
+// HIGHLIGHT: INFORMATION
+
+fun foo(arg: Int): Int {
+    <caret>when (arg) {
+        0 -> return 0
+        else -> throw Exception()
+    }
+}

idea/testData/inspectionsLocal/liftOut/whenToReturn/whenOneReturn.kt.after

@@ -0,0 +1,8 @@
+// HIGHLIGHT: INFORMATION
+
+fun foo(arg: Int): Int {
+    return when (arg) {
+        0 -> 0
+        else -> throw Exception()
+    }
+}

idea/testData/inspectionsLocal/liftOut/whenToReturn/whenThrowOnly.kt

@@ -0,0 +1,7 @@
+// PROBLEM: none
+
+fun foo(): Int {
+    <caret>when {
+        else -> throw Exception()
+    }
+}