Please add Azure Web PubSub to the Azure functions extension bundle

Currently, [Microsoft.Azure.WebJobs.Extensions.WebPubSub](https://www.nuget.org/packages/Microsoft.Azure.WebJobs.Extensions.WebPubSub/1.0.0-beta.3) is not a part of the functions extension bundle and I'm forced to register it separately.

```
func extensions install --package Microsoft.Azure.WebJobs.Extensions.WebPubSub --version 1.0.0-beta.3
```

Would it be possible to add this package to the [functions extension bundle](https://github.com/Azure/azure-functions-extension-bundles)?

Start with the linked Azure Functions extension bundle repository and the Microsoft.Azure.WebJobs.Extensions.WebPubSub package reference shown in the issue. Check how extension bundle packages and versions are declared, then verify that version 1.0.0-beta.3 is included and the separate func extensions install command is no longer required.

Written by the indexing model from the issue text.