[Server] Emit Notification on Capability Change

[chr-hertel]

The specification lists server emitting notifications, whenever a list of capabilities for the client changes:

For this we would need support from dispatching events in the Registry to creating notifications for

• ResourceListChangedNotification
• PromptListChangedNotification
• ToolListChangedNotification

(There are more server notification, but less connected to this scenario.)

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Please announce yourself before working on this - so we can avoid duplicate effort.

[Bellangelo]

I am giving it a go at the moment.