Generate bridges for trait implementations properly

The intent was to keep the bridge codegen model as simple as possible: we
should be able to figure out all necessary bridges only by a minimal interface
that FunctionHandle provides (isAbstract, isDeclaration, getOverridden)

Add different tests for bridges

 #KT-318 Obsolete

compiler/testData/codegen/box/bridges/fakeOverrideWithImplementationInTrait.kt

@@ -0,0 +1,18 @@
+trait A {
+    fun foo(): String = "A"
+}
+
+trait B {
+    fun foo(): Any
+}
+
+class C : A, B
+
+fun box(): String {
+    val c = C()
+    var result = ""
+    result += c.foo()
+    result += (c : B).foo()
+    result += (c : A).foo()
+    return if (result == "AAA") "OK" else "Fail: $result"
+}