Understand the consequences of needing an async room attach prior to presence ops

[umair-ably]

Whilst we've implemented the spec points under ECO-4948, it's only increased the confusion of this requirement. We should better understand and document this change as it does suddenly make interacting with the SDK slightly more complicated (at least in the understanding of potential behaviours).

Equally, we need to explore more unhappy paths and provide good examples of how we expect users to interact with our SDK. Specific issue for this point can be found here

┆Issue is synchronized with this Jira Task by Unito