Implicit Nothing? type: don't report when declaration overrides nullable nothing type

#KT-30481 Fixed

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideFunction.kt

@@ -0,0 +1,7 @@
+abstract class Parent {
+    protected abstract fun foo(): String?
+}
+
+class Child : Parent() {
+    override fun <caret>foo() = null
+}

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideFunction.kt.after

@@ -0,0 +1,7 @@
+abstract class Parent {
+    protected abstract fun foo(): String?
+}
+
+class Child : Parent() {
+    override fun foo(): Nothing? = null
+}

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideNullableNothingFunction.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+abstract class Parent {
+    protected abstract fun foo(): Nothing?
+}
+
+class Child : Parent() {
+    override fun <caret>foo() = null
+}

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideNullableNothingProperty.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+abstract class Parent {
+    abstract val foo: Nothing?
+}
+
+class Child : Parent() {
+    override val <caret>foo = null
+}

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideProperty.kt

@@ -0,0 +1,7 @@
+abstract class Parent {
+    abstract val foo: Int?
+}
+
+class Child : Parent() {
+    override val <caret>foo = null
+}

idea/testData/inspectionsLocal/implicitNullableNothingType/overrideProperty.kt.after

@@ -0,0 +1,7 @@
+abstract class Parent {
+    abstract val foo: Int?
+}
+
+class Child : Parent() {
+    override val foo: Nothing? = null
+}