Add test verifying multiple tags per measurement display correctly

Adds a regression test for issue #5683 that explicitly verifies
when a measurement has multiple tags (e.g. ExistingTag=Value1,NewTag=Value2),
all tags are displayed in the console output.

Note: This test passes both with and without the defensive code
improvements in ConsoleWriter.cs, suggesting the core multi-tag
functionality was already working. The defensive code improvements
still add value by preventing potential crashes on malformed input.

Author: steveisok

src/tests/dotnet-counters/ConsoleExporterTests.cs

@@ -284,26 +284,28 @@ public void LongMultidimensionalTagsAreTruncated()
         public void MultipleTagsPerMeasurementAreDisplayed()
         {
             // Regression test for issue #5683
-            // Verifies that when a single measurement has multiple tags,
-            // all tags are displayed correctly
-            MockConsole console = new MockConsole(70, 40);
+            // User reported that when adding a second tag to their ObservableGauge/ObservableCounter,
+            // only the first tag was displayed and the second tag (NewTag) was not shown
+            MockConsole console = new MockConsole(90, 40);  // Wide console to see both tags clearly
             ConsoleWriter exporter = new ConsoleWriter(console);
             exporter.Initialize();
 
-            // Simulate ObservableGauge/ObservableCounter with multiple tags per measurement
+            // Simulate a single measurement with two tags: ExistingTag and NewTag
+            // This matches the user's code: new Measurement<long>(value, 
+            //   new KeyValuePair("ExistingTag", Value1), 
+            //   new KeyValuePair("NewTag", "Value2"))
             exporter.CounterPayloadReceived(CreateMeterCounterPreNet8("MyApp", "RequestCount", "{requests}", "ExistingTag=Value1,NewTag=Value2", 100), false);
-            exporter.CounterPayloadReceived(CreateMeterCounterPreNet8("MyApp", "RequestCount", "{requests}", "ExistingTag=Value3,NewTag=Value4", 200), false);
 
+            // Both tags should be displayed as columns
             console.AssertLinesEqual("Press p to pause, r to resume, q to quit.",
                                      "    Status: Running",
                                      "",
-                                     "Name                                        Current Value",
+                                     "Name                                                                         Current Value",
                                      "[MyApp]",
                                      "    RequestCount ({requests} / 1 sec)",
                                      "        ExistingTag NewTag",
                                      "        ----------- ------",
-                                     "        Value1      Value2                         100",
-                                     "        Value3      Value4                         200");
+                                     "        Value1      Value2                                                         100");
         }
 
         [Fact]