Change API: Return Space Property instead of String

The space console should return a space property instances instead of a plain string. Prior we only had properties that do not need any additional rendering. Now we are about to redesign this issue.

In addition to that we need to allow clients to assess on which the property has been set. This is necessary for use cases where the property assumes the space it is part of, but does not provided any reference to that space. This is the case with links that reference a page on the space the property is set. This link does per default not contain a reference to its space. Clients should be able to determine which space provides the property.