JS: fix copying functions with default arguments across interfaces

Copy function to super interface first, then copy from interface
to class. Add interface set to JsClassModel for this purpose.

See KT-20625

js/js.translator/testData/box/defaultArguments/inheritViaAnotherInterface.kt

@@ -0,0 +1,82 @@
+// EXPECTED_REACHABLE_NODES: 1147
+// FILE: classes.kt
+class C : J
+
+class D : J {
+    override fun foo(x: String): String = "D.foo($x)"
+}
+
+class E : J {
+    override fun bar(x: String): String = "E.bar($x)"
+}
+
+class F : L {
+    override fun bar(x: String): String = "F.bar($x)"
+}
+
+interface I {
+    fun foo(x: String = "Q"): String = "I.foo($x)"
+
+    fun bar(x: String = "Q"): String = "I.bar($x)"
+}
+
+interface J : I {
+    override fun foo(x: String): String = "J.foo($x)"
+}
+
+interface K {
+    fun foo(x: String = "Q"): String
+
+    fun bar(x: String = "Q"): String
+}
+
+interface L : K {
+    override fun foo(x: String): String = "L.foo($x)"
+}
+
+// FILE: main.kt
+// RECOMPILE
+fun box(): String {
+    var o: I = C()
+
+    var r = o.foo()
+    if (r != "J.foo(Q)") return "fail C.foo(): $r"
+    r = o.foo("W")
+    if (r != "J.foo(W)") return "fail C.foo(W): $r"
+    r = o.bar()
+    if (r != "I.bar(Q)") return "fail C.bar(): $r"
+    r = o.bar("W")
+    if (r != "I.bar(W)") return "fail C.bar(W): $r"
+
+    o = D()
+    r = o.foo()
+    if (r != "D.foo(Q)") return "fail D.foo(): $r"
+    r = o.foo("W")
+    if (r != "D.foo(W)") return "fail D.foo(W): $r"
+    r = o.bar()
+    if (r != "I.bar(Q)") return "fail D.bar(): $r"
+    r = o.bar("W")
+    if (r != "I.bar(W)") return "fail D.bar(W): $r"
+
+    o = E()
+    r = o.foo()
+    if (r != "J.foo(Q)") return "fail E.foo(): $r"
+    r = o.foo("W")
+    if (r != "J.foo(W)") return "fail E.foo(W): $r"
+    r = o.bar()
+    if (r != "E.bar(Q)") return "fail E.bar(): $r"
+    r = o.bar("W")
+    if (r != "E.bar(W)") return "fail E.bar(W): $r"
+
+    val p: K = F()
+    r = p.foo()
+    if (r != "L.foo(Q)") return "fail F.foo(): $r"
+    r = p.foo("W")
+    if (r != "L.foo(W)") return "fail F.foo(W): $r"
+    r = p.bar()
+    if (r != "F.bar(Q)") return "fail F.bar(): $r"
+    r = p.bar("W")
+    if (r != "F.bar(W)") return "fail F.bar(W): $r"
+
+    return "OK"
+}