FIR: Fix label/receiver for lambda within infix calls

While this fix only changes label name, it's important for proper
lambda resolution because receiver is set for a lambda
only in presence of a label

This commit fixes a lot of checkType calls in diagnostic tests

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

@@ -0,0 +1,14 @@
+class A {
+    fun bar() {}
+}
+
+infix fun (() -> Unit).foo(x: A.() -> Unit) {}
+
+fun main() {
+    {
+        return@foo
+    } foo {
+        bar()
+        return@foo
+    }
+}