Filter out equivalent calls before reporting "none applicable"

If a module is configured in such a way that the same function appears multiple
times via different dependencies, it's not helpful to report "none of the
following functions can be called", listing the same function multiple times

compiler/testData/diagnostics/tests/multimodule/duplicateMethod/incompleteCodeNoNoneApplicable.txt

@@ -0,0 +1,25 @@
+// -- Module: <m1> --
+package
+
+package p {
+    public fun f(/*0*/ s: kotlin.String, /*1*/ t: kotlin.String): kotlin.String
+}
+
+
+// -- Module: <m2> --
+package
+
+package p {
+    public fun f(/*0*/ s: kotlin.String, /*1*/ t: kotlin.String): kotlin.String
+}
+
+
+// -- Module: <m3> --
+package
+
+public fun test(): kotlin.Unit
+
+package p {
+    public fun f(/*0*/ s: kotlin.String, /*1*/ t: kotlin.String): kotlin.String
+    public fun f(/*0*/ s: kotlin.String, /*1*/ t: kotlin.String): kotlin.String
+}