[BugBash][Cli] `az webpubsub hub` should indicate which argument is wrong.

[JialinXin]

Describe the bug

When input invalid argument, it simply shows (BadArgument) Invalid arguments without more details. And is hard to find out which parameter has problem.

To Reproduce

az webpubsub hub create --hub-name "aaa" --name "jixin-teststd" --resource-group "jixin-bugbash" --allow-anonymous --event-handler url-template="http://localhost" user-event-pattern=* system-event=connect

[zackliu]

https://github.com/Azure/azure-cli-extensions/pull/4049