FIR checker: warn useless as and is

compiler/fir/analysis-tests/testData/resolve/cfg/when.kt

@@ -13,6 +13,6 @@ interface B
 
 fun test_2(x: Any?) {
     if (x is A && x is B) {
-        x is A
+        <!USELESS_IS_CHECK!>x is A<!>
     }
 }

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_sealedSubClass.kt

@@ -27,7 +27,7 @@ fun test_1(e: A) {
 
     val d = when (e) {
         is E -> 1
-        is A -> 2
+        <!USELESS_IS_CHECK!>is A<!> -> 2
     }.plus(0)
 }
 

compiler/fir/analysis-tests/testData/resolve/expresssions/when.kt

@@ -1,6 +1,6 @@
 fun foo() = if (true) 1 else 0
 
 fun bar(arg: Any?) = when (arg) {
-    is Int -> arg as Int
+    is Int -> arg <!USELESS_CAST!>as Int<!>
     else -> 42
 }

compiler/fir/analysis-tests/testData/resolve/typesInLocalFunctions.kt

@@ -3,7 +3,7 @@ class Some
 fun foo(): () -> Boolean {
     val s = Some()
     if (true) {
-        return { if (s is Some) true else false }
+        return { if (<!USELESS_IS_CHECK!>s is Some<!>) true else false }
     } else {
         return { true }
     }