Tests/usage of mirroring and stream sourcing

[mtmk]

          Due to the difficulty of automating leaf node testing below are examples of tests/usage of mirroring and stream sourcing.

   [Fact]
   public async Task Test_LeafStreamMirrorDomain()
   {
       await using var natsLeaf = new NatsConnection(new NatsOpts { Url = "nats://leaf:4223/", AuthOpts = new NatsAuthOpts { Username = "leaf", Password = "leaf" } });
       await natsLeaf.ConnectAsync();

       var jsContext = new NatsJSContext(natsLeaf);

       var mirroredStream = await jsContext.CreateStreamAsync(new StreamConfig()
       {
           Name = "mirroredStream",
           Mirror = new StreamSource
           {
               Name = "sourceStream1",
               Domain = "hub",
           },
       });
   }

   [Fact]
   public async Task Test_LeafStreamMultiSourceDomain()
   {
       await using var natsLeaf = new NatsConnection(new NatsOpts { Url = "nats://leaf:4223/", AuthOpts = new NatsAuthOpts { Username = "leaf", Password = "leaf" } });
       await natsLeaf.ConnectAsync();

       var jsContext = new NatsJSContext(natsLeaf);

       var mirroredStream = await jsContext.CreateStreamAsync(new StreamConfig()
       {
           Name = "mirroredStreamMulti",
           Sources = [
                   new StreamSource { Name = "sourceStream1", Domain = "hub" },
                   new StreamSource { Name = "sourceStream2", Domain = "hub" }
               ],
       });
   }

   [Fact]
   public async Task Test_LeafKVMirrorDomain()
   {
       await using var natsLeaf = new NatsConnection(new NatsOpts { Url = "nats://leaf:4223/", AuthOpts = new NatsAuthOpts { Username = "leaf", Password = "leaf" } });
       await natsLeaf.ConnectAsync();

       var jsContext = new NatsJSContext(natsLeaf);
       var kvContext = new NatsKVContext(jsContext);

       var mirroredStore = await kvContext.CreateStoreAsync(new NatsKVConfig("mirroredKvTestMirror")
       {
           Mirror = new StreamSource
           {
               Name = "kvTest",
               Domain = "hub",
           },
       });
   }

   [Fact]
   public async Task Test_LeafKVMirrorSourcesDomain()
   {
       await using var natsLeaf = new NatsConnection(new NatsOpts { Url = "nats://leaf:4223/", AuthOpts = new NatsAuthOpts { Username = "leaf", Password = "leaf" } });
       await natsLeaf.ConnectAsync();

       var jsContext = new NatsJSContext(natsLeaf);
       var kvContext = new NatsKVContext(jsContext);

       var mirroredStore = await kvContext.CreateStoreAsync(new NatsKVConfig("mirroredKvTestSources")
       {
           Sources = [
                   new StreamSource { Name = "kvTest", Domain = "hub" },
           ],
       });
   }

Originally posted by @darkwatchuk in #631 (comment)