Suggested rooms spaces

Add the ability to set and show suggested rooms for spaces. 

This is just adding the basic functionality, we can do more things with it later like sort/filter the space home for example.

src/models/spacechildrenmodel.h

@@ -44,6 +44,7 @@ public:
         WorldReadableRole,
         IsJoinedRole,
         IsSpaceRole,
+        IsSuggestedRole,
         CanAddChildrenRole,
         ParentDisplayNameRole,
         CanSetParentRole,