Allow accessing message payload for realtime in RLS policies

[ferhatwi]

Listening presence of users in a room can be done by this:

const roomOne = supabase.channel('room_01')

const userStatus = {
  user: USER_ID,
  online_at: new Date().toISOString(),
}

roomOne.subscribe(async (status) => {
  if (status !== 'SUBSCRIBED') { return }

  const presenceTrackStatus = await roomOne.track(userStatus)
  console.log(presenceTrackStatus)
})

But this way, we can't be sure that USER_ID is indeed the id of the user that joins the presence channel, since we can't check if the value of the user key of payload equals auth.uid() in Row Level Security's insert policies.

[jacobrobertsbaca]

Bumping this