react-sdk: gdm support

[miguel-nascimento]

• useGdm: return metadata from a gdm
• useUserGdms: return all gdms where the current user is a member
• useChannelTimeline: gets the timeline from a channel using the channel and space id
• useGdmTimeline: gets the timeline from a gdm using the streamId
• useRiverConnection got rename to useAgentConnection
  • the previous name was confusing, since the connection status was about the sync agent being defined and not about the river auth connection status.
• useSendMessage now accepts the id of either gdm or a space & channel

did some changes in the UI to support /m/:gdmStreamId

fixed some issues related to login, now when you click disconnect you get redirected back to /auth