Notification & NotificationGroup: Unify and cleanup props

[MarcusNotheis]

All UI5 Web Component props of type boolean are set to false by default and they are often prefixed with no.., e.g. noIcon, noCloseButton, etc. We should adopt to this convention as well.

Rename Props:

• rename prop hideShowMoreButton to noShowMoreButton
• rename prop showCloseButton to noCloseButton
• remove default prop showCloseButton ( will result in falsy value)

Remove Props:

• remove prop visible, the consumer of the API should take care of that by using conditional rendering
• remove isChild as this is an internal API which shouldn't be used by the consumers, change access to object access to avoid TS errors
• remove isLastChild as this is an internal API which shouldn't be used by the consumers, change access to object access to avoid TS errors