[FE 1.0] Fix false-negative INVALID_IF_AS_EXPRESSION_WARNING and NO_ELSE_IN_WHEN_WARNING

^KT-51711 Fixed

compiler/testData/diagnostics/tests/controlStructures/kt51711.kt

@@ -0,0 +1,22 @@
+// FIR_IDENTICAL
+// LANGUAGE: -ProhibitNonExhaustiveIfInRhsOfElvis
+// ISSUE: KT-51711
+// WITH_STDLIB
+
+private fun fake(a: String?) {}
+
+fun test_1(x: String?, y: String?) {
+    while (true) {
+        x ?: if (y == null) break else fake(y)
+    }
+}
+
+
+fun test_2(x: String?, y: String?) {
+    while (true) {
+        x ?: when {
+            true -> break
+            else -> y?.filter { it.isLowerCase() }
+        }
+    }
+}

compiler/testData/diagnostics/tests/controlStructures/kt51711.txt

@@ -0,0 +1,5 @@
+package
+
+private fun fake(/*0*/ a: kotlin.String?): kotlin.Unit
+public fun test_1(/*0*/ x: kotlin.String?, /*1*/ y: kotlin.String?): kotlin.Unit
+public fun test_2(/*0*/ x: kotlin.String?, /*1*/ y: kotlin.String?): kotlin.Unit