FIR: Adjust testData for spec tests: invoke on nullable receiver

It's a design problem, see related issue

^KT-30415

compiler/fir/analysis-tests/testData/resolve/problems/safeCallInvoke.kt

@@ -0,0 +1,13 @@
+class A {
+    operator fun invoke() {}
+}
+
+class B {
+    val bar: () -> Unit = {}
+    val foo: A = A()
+}
+
+fun main(b: B?) {
+    b?.bar() // allowed in FIR, prohibited in old FE
+    b?.foo() // allowed in FIR, prohibited in old FE
+}

compiler/fir/analysis-tests/testData/resolve/problems/safeCallInvoke.txt

@@ -0,0 +1,29 @@
+FILE: safeCallInvoke.kt
+    public final class A : R|kotlin/Any| {
+        public constructor(): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final operator fun invoke(): R|kotlin/Unit| {
+        }
+
+    }
+    public final class B : R|kotlin/Any| {
+        public constructor(): R|B| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final val bar: R|() -> kotlin/Unit| = fun <anonymous>(): R|kotlin/Unit| {
+            ^ Unit
+        }
+
+            public get(): R|() -> kotlin/Unit|
+
+        public final val foo: R|A| = R|/A.A|()
+            public get(): R|A|
+
+    }
+    public final fun main(b: R|B?|): R|kotlin/Unit| {
+        R|<local>/b|?.R|/B.bar|?.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
+        R|<local>/b|?.R|/B.foo|?.R|/A.invoke|()
+    }