FIR checker: warn useless as and is

compiler/testData/diagnostics/testsWithStdLib/cast/IsArray.fir.kt

@@ -1,5 +1,5 @@
 fun f(a: Array<out Number>) = a.isArrayOf<Int>()
 
-fun f1(a: Array<out Number>) = a is Array<*>
+fun f1(a: Array<out Number>) = <!USELESS_IS_CHECK!>a is Array<*><!>
 
-fun f2(a: Array<out Number>) = a is Array<Int>
+fun f2(a: Array<out Number>) = a is Array<Int>

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/deeplyNested.fir.kt

@@ -95,7 +95,7 @@ fun branchedAndNestedWithNativeOperators(x: Any?, y: Any?) {
                     equalsTrue(isInt(y) && isString(y))                          // y is Int, String
             )
             &&
-            (1 == 2 || y is Int || isString(y))
+            (1 == 2 || <!USELESS_IS_CHECK!>y is Int<!> || isString(y))
     )
     x.length
     y.length

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.fir.kt

@@ -1,11 +0,0 @@
-// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
-// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
-// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
-
-import kotlin.contracts.*
-
-fun f3(value: String?) {
-    if (!value.isNullOrEmpty() is Boolean) {
-        value<!UNSAFE_CALL!>.<!>length
-    }
-}

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
 // !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
 // !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER