Add web-pubsub to CI, update samples

[bterlson]

Preparing to release the first beta package 😁

@willmtemple found that the product slugs used weren't initialized, removing them for now. @vicancy can you follow up with the docs team to add the proper product slugs for the service (presumably azure-web-pubsub)?

Regenerated samples and found that web-pubsub-express didn't check in the "camera ready" samples", so adding them here.

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[bterlson]

/azp run prepare-pipelines

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[bterlson]

/azp run js - web-pubsub - ci

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[witemple-msft]

LGTM