Keep some agent start across restarts, such as the SSE manager and
observer. This allows restarts to be shown on the state page and also
allows avatars to be kept when reconfiguring the agent.
Also observable updates can happen out of order because SSE manager has
multiple workers. For now handle this in the client.
Finally fix an issue with the IRC client to make it disconnect and
handle being assigned a different nickname by the server.
Signed-off-by: Richard Palethorpe <io@richiejp.com>
f289e824df