Public preview: Microsoft Azure Web PubSub Premium Tier

Azure Web PubSub Premium tier is in preview. This plan provides greater resiliency, scalability and flexibility by enabling key features, including: * An SLA including 99.95% availability. * [Availability Zone support:](https://docs.microsoft.com/en-us/azure/azure-web-pubsub/concept-availability-zones) Distribute workloads evenly across multiple zones in a supported Azure region, and redirect traffic to other zones in the event of a failure. * Autoscale capabilities: Specify rules that make it easy scale up and down to meet capacity needs and optimise resource usage. * [Custom domain support:](https://docs.microsoft.com/en-us/azure/azure-web-pubsub/howto-custom-domain?tabs=azure-powershell) Add your desired custom domain names to your application. * Azure web PubSub * Features * [ Azure web PubSub](https://azure.microsoft.com/en-gb/products/web-pubsub/)