Introduce inspection for determining if a forEach parameter is unused

#KT-22068 Fixed

idea/testData/inspections/forEachParameterNotUsed/correctReference.kt

@@ -0,0 +1,10 @@
+fun test() {
+    val items = sequenceOf<Any>()
+    items.forEach {
+        ForEachable().forEach {}
+    }
+}
+
+class ForEachable {
+    fun forEach(action: (ForEachable) -> Unit) {}
+}

idea/testData/inspections/forEachParameterNotUsed/inspectionData/expected.xml

@@ -0,0 +1,34 @@
+<problems>
+  <problem>
+    <file>test.kt</file>
+    <line>3</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/test.kt" />
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Iterated elements are not used in forEach</problem_class>
+    <description>Loop parameter 'it' is unused</description>
+  </problem>
+  <problem>
+    <file>test.kt</file>
+    <line>4</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/test.kt" />
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Iterated elements are not used in forEach</problem_class>
+    <description>Loop parameter 'item' is unused</description>
+  </problem>
+  <problem>
+    <file>test.kt</file>
+    <line>7</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/test.kt" />
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Iterated elements are not used in forEach</problem_class>
+    <description>Loop parameter 'it' is unused</description>
+  </problem>
+  <problem>
+    <file>correctReference.kt</file>
+    <line>3</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/correctReference.kt" />
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Iterated elements are not used in forEach</problem_class>
+    <description>Loop parameter 'it' is unused</description>
+  </problem>
+</problems>

idea/testData/inspections/forEachParameterNotUsed/inspectionData/inspections.test

@@ -0,0 +1,2 @@
+// INSPECTION_CLASS: org.jetbrains.kotlin.idea.inspections.ForEachParameterNotUsedInspection
+// WITH_RUNTIME

idea/testData/inspections/forEachParameterNotUsed/test.kt

@@ -0,0 +1,11 @@
+fun test() {
+    val items = listOf<Any>()
+    items.forEach { }
+    items.forEach { item -> }
+    items.forEach { doSomething(it) }
+    items.forEach { item -> doSomething(item) }
+    items.forEach { items.forEach { doSomething(it) } }
+    items.forEach { items.forEach { thing -> doSomething(it); doSomething(thing) } }
+}
+
+fun doSomething(item: Any) {}