To be more consistent with similar code. The check now automatically
raises an AuthError instead of passing back a boolean. It also absorbs
some shared logic between callers.
When receiving a /send_join request for a room with join rules set to 'restricted',
check if the user is a member of the spaces defined in the 'allow' key of the join rules.
This only applies to an experimental room version, as defined in MSC3083.
When receiving a /send_join request for a room with join rules set to 'restricted',
check if the user is a member of the spaces defined in the 'allow' key of the join
rules.
This only applies to an experimental room version, as defined in MSC3083.
