Inspections: Add inspection on equals()/hashCode()

idea/testData/inspections/equalsAndHashCode/test.kt

@@ -0,0 +1,39 @@
+class C1 {
+    override fun equals(other: Any?) = true
+}
+
+class C2 {
+    override fun hashCode() = 0
+}
+
+class C3 {
+    override fun equals(other: Any?) = true
+    override fun hashCode() = 0
+}
+
+object O1 {
+    override fun equals(other: Any?) = true
+}
+
+object O2 {
+    override fun hashCode() = 0
+}
+
+object O3 {
+    override fun equals(other: Any?) = true
+    override fun hashCode() = 0
+}
+
+class C4 {
+    override fun equals(other: С4) = true
+}
+
+interface I {
+    override fun equals(other: Any?) = true
+    override fun hashCode() = 0
+}
+
+enum E {
+    override fun equals(other: Any?) = true
+    override fun hashCode() = 0
+}