Improve header/impl mismatch diagnostic messages

Try to report most mismatch errors on the 'impl' declaration. Only
report a mismatch error on the 'header' declaration if no error would be
otherwise reported on any 'impl' declaration in the compilation unit.
Also render declaration kind in the message

 #KT-18447 In Progress

compiler/tests/org/jetbrains/kotlin/multiplatform/MultiPlatformIntegrationTestGenerated.java

@@ -96,6 +96,12 @@ public class MultiPlatformIntegrationTestGenerated extends AbstractMultiPlatform
         doTest(fileName);
     }
 
+    @TestMetadata("missingOverload")
+    public void testMissingOverload() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/multiplatform/missingOverload/");
+        doTest(fileName);
+    }
+
     @TestMetadata("simple")
     public void testSimple() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/multiplatform/simple/");