Generate equals()/hashCode(): Forbid in interfaces

#KT-10815 Fixed

idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateEqualsAndHashcodeAction.kt

@@ -69,7 +69,10 @@ class KotlinGenerateEqualsAndHashcodeAction : KotlinGenerateMemberActionBase<Kot
     )
 
     override fun isValidForClass(targetClass: KtClassOrObject): Boolean {
-        return targetClass is KtClass && targetClass !is KtEnumEntry && !targetClass.isAnnotation()
+        return targetClass is KtClass
+               && targetClass !is KtEnumEntry
+               && !targetClass.isAnnotation()
+               && !targetClass.isInterface()
                && !targetClass.hasModifier(KtTokens.DATA_KEYWORD)
                && getPropertiesToUseInGeneratedMember(targetClass).isNotEmpty()
     }

idea/testData/codeInsight/generate/equalsWithHashCode/interface.kt

@@ -1,6 +1,4 @@
 // NOT_APPLICABLE
 interface A {<caret>
-    fun foo() {
-
-    }
+    val foo: Int
 }