New LastWillAndTestament Builder

[pglombardo]

Description

This PR adds a new builder class for LastWillAndTestament:

var lwt = new LastWillAndTestamentBuilder()
            .WithTopic("last/will")
            .WithPayload("last will message")
            .WithQualityOfServiceLevel(QualityOfService.AtLeastOnceDelivery)
            .WithContentType("application/text")
            .WithResponseTopic("response/topic")
            .WithCorrelationData(new byte[] { 1, 2, 3, 4, 5 })
            .WithPayloadFormatIndicator(MQTT5PayloadFormatIndicator.UTF8Encoded)
            .WithMessageExpiryInterval(100)
            .WithUserProperty("userPropertyKey", "userPropertyValue")
            .WithWillDelayInterval(1)
            .Build();

        // Setup & Connect the client with LWT
        var options = new HiveMQClientOptions
        {
            LastWillAndTestament = lwt,
        };

        var client = new HiveMQClient(options);
        connectResult = await client.ConnectAsync().ConfigureAwait(false);

Related Issue

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

Checklist

• I've written tests (if applicable) for all new methods and classes that I created. (rake test)
• I've added documentation as necessary so users can easily use and understand this feature/fix.