feat: add Reachability Center and Why Drawer components with tests

- Implemented ReachabilityCenterComponent for displaying asset reachability status with summary and filtering options.
- Added ReachabilityWhyDrawerComponent to show detailed reachability evidence and call paths.
- Created unit tests for both components to ensure functionality and correctness.
- Updated accessibility test results for the new components.

src/Concelier/StellaOps.Concelier.Tests.Shared/ConcelierFixtureCollection.cs

@@ -0,0 +1,9 @@
+using Xunit;
+
+namespace StellaOps.Concelier.Testing;
+
+[CollectionDefinition(ConcelierFixtureCollection.Name, DisableParallelization = true)]
+public sealed class ConcelierFixtureCollection : ICollectionFixture<ConcelierPostgresFixture>
+{
+    public const string Name = "ConcelierPostgres";
+}

src/Concelier/StellaOps.Concelier.Tests.Shared/MongoFixtureCollection.cs

@@ -1,6 +0,0 @@
-using Xunit;
-
-namespace StellaOps.Concelier.Testing;
-
-[CollectionDefinition("mongo-fixture", DisableParallelization = true)]
-public sealed class MongoFixtureCollection : ICollectionFixture<MongoIntegrationFixture>;