[FIR] Skip expect-actual rules check when overriding non-expect member

Overriding equals, hashCode, toString and any other member that is not
expect does not require satisfying the rules of expect-actual matching.

#KT-57381 Fixed

compiler/testData/codegen/box/multiplatform/k2/basic/nonExternalEquals.kt

@@ -0,0 +1,27 @@
+// !LANGUAGE: +MultiPlatformProjects
+// IGNORE_BACKEND_K1: ANY
+// IGNORE_BACKEND: WASM
+// MODULE: common
+// FILE: common.kt
+
+open class Base {
+    open operator fun plus(b: Base) = Base()
+}
+
+expect open class Derived constructor() : Base() {
+}
+
+// MODULE: main()()(common)
+// FILE: main.kt
+
+actual open class Derived : Base() {
+    // Any.equals is is external on Native but because it's not expect, it's ok to override without external
+    override fun equals(other: Any?): Boolean = other === this
+    override fun hashCode() = 1
+    override fun toString() = "Derived"
+
+    // no operator modifier is legal because Base.plus is not expect
+    override fun plus(b: Base) = Derived()
+}
+
+fun box() = "OK"