Introduce FirFunctionReturnTypeMismatchChecker

compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt

@@ -111,8 +111,8 @@ fun testTwoLambdas() {
 }
 
 fun f1(): (() -> Unit) -> (() -> Unit) -> Unit {
-    return { l1 ->
+    return <!RETURN_TYPE_MISMATCH!>{ l1 ->
         l1()
         <!TOO_MANY_ARGUMENTS!>{ l2 -> <!UNRESOLVED_REFERENCE!>l2<!>() }<!>
-    }
+    }<!>
 }