Is your feature request related to a problem? Please describe.

With the work done in #15513 + #15514 we now need to fulfil a few items in order to enable the auto-generation of the documentation part for the Shell API:

• Update Shell API's methods usage signature to a pattern more "up-to-date" and easy to be consumed
• Integrate the Notification Center as a Shell API
• Add information for when the Shell API is available to be consumed (to the docs page)
• Update typedoc integration to auto-generate new documentation

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