Split or glue together checks for not null and is instance + more intelligent use of filter vs filterTo

#KT-14284 Fixed
 #KT-14286 Fixed
 #KT-14287 Fixed
 #KT-14303 Fixed

idea/testData/intentions/loopToCallChain/indexOf/KT14303.kt

@@ -0,0 +1,11 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'indexOfFirst{}'"
+// IS_APPLICABLE_2: false
+fun f8_indexOfFirst_complex(value: String, list: List<Any?>):Int{
+    <caret>for ((i, any) in list.withIndex())
+        if (any != null)
+            if (any is String)
+                if (any == value)
+                    return i
+    return -1
+}

idea/testData/intentions/loopToCallChain/indexOf/KT14303.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'indexOfFirst{}'"
+// IS_APPLICABLE_2: false
+fun f8_indexOfFirst_complex(value: String, list: List<Any?>):Int{
+    return list.indexOfFirst { it != null && it is String && it == value }
+}