Select most specific overloaded function/property by explicitly used arguments only.

Major rewrite of OverloadingConflictResolver.

compiler/testData/diagnostics/tests/resolve/overloadConflicts/extensionReceiverAndVarargs.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+interface IA
+interface IB : IA
+fun IA.foo(vararg x: Int) = Wrong
+fun IB.foo(vararg x: Int) = Right
+class CC : IB
+
+val test7 = CC().foo(1, 2, 3)