feat(batch50): merge JetStream cluster 1 tests and fix build errors

- Added ShouldSkip() and ServerRuntimeUnavailable to IntegrationTestBase
- Fixed WaitOnPeerCount -> WaitOnClusterReady
- Fixed using -> await using for NatsConnection (IAsyncDisposable)
- Removed duplicate PackageReference entries from csproj

dotnet/tests/ZB.MOM.NatsNet.Server.IntegrationTests/Helpers/IntegrationTestBase.cs

@@ -45,6 +45,19 @@ public abstract class IntegrationTestBase : IDisposable
     /// <summary>xUnit output helper, available to derived test classes.</summary>
     protected ITestOutputHelper Output { get; }
 
+    /// <summary>
+    /// Returns true if integration tests should be skipped.
+    /// Convenience method for use in individual test methods that call
+    /// <c>Skip.If(ShouldSkip(), "reason")</c>.
+    /// </summary>
+    protected static bool ShouldSkip() => !Helpers.TestServerHelper.CanBoot();
+
+    /// <summary>
+    /// Returns true if the server runtime is unavailable.
+    /// Alias for <see cref="ShouldSkip"/> used by some test batches.
+    /// </summary>
+    protected static bool ServerRuntimeUnavailable => !Helpers.TestServerHelper.CanBoot();
+
     // =========================================================================
     // IDisposable
     // =========================================================================