Check for the presence of dispatch receiver too in isEqualsDescriptor()

Otherwise, top-level function with the name 'equals' and suitable
signature will be (erroneously) treated as true 'equals' invocation,
leading to further exception (see EA-126602)

compiler/testData/diagnostics/tests/override/fakeEquals.kt

@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_REFERENCE
+
+class Foo
+
+fun test(a: Foo, b: Foo) {
+    // Note that signature matches the 'equals'
+    fun equals(x: Any?): Boolean = false
+    equals(b)
+}

compiler/testData/diagnostics/tests/override/fakeEquals.txt

@@ -0,0 +1,10 @@
+package
+
+public fun test(/*0*/ a: Foo, /*1*/ b: Foo): kotlin.Unit
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}