Improve offline character management settings for spaces

[ClaudiaMia]

Currently, the rights management setting "Offline Character Management" affects the whole space. But this is not fine-grained enough in many cases and also most new users do not set it, which is a burden for popular public spaces.

Proposals:

• Change the offline character management to default: true [to be discussed]
• Change the default of the setting to also affect characters in slots of room-level item to "true"
• Add a new setting: Also affects the space when it is private or protected (default: false)
• Add a new room setting feature that allows to set if an individual room is affected by an active offline character management or not. Default for all rooms is "true". (idea by Sandrine)