FIR checker: report REDUNDANT_LABEL_WARNING

Since many labels are not present in the FIR tree, this checker is
implemented as a syntax checker. Comparing with FE1.0, this change
reports some REDUNDANT_LABEL_WARNING that FE1.0 has missed, especially
LHS of assignments.

compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.fir.kt

@@ -1,20 +0,0 @@
-interface Foo<T>
-
-class Bar {
-    operator fun <T> invoke(): Foo<T> = throw Exception()
-}
-
-class A {
-    val bar = Bar()
-}
-
-fun fooInt(l: Foo<Int>) = l
-
-fun test(bar: Bar, a: A) {
-    // no elements with error types
-    fooInt((bar()))
-    fooInt(if (true) bar() else bar())
-    fooInt(label@ bar())
-    fooInt(a.bar())
-    fooInt(((label@ if (true) (a.bar()) else bar())))
-}

compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface Foo<T>
 
 class Bar {