Add two separate toggles to control event loop pausing. This is required
to prevent cases where the bridge requests the event loop to be paused
but a sync process completes and resumes the event loop.
For the loop to resume now both states need to be set to false. This
will be removed once GODT-2848 is implemented.
Wait for the current event poll to finish publishing events after a
request to pause the event loop. This is required to change the gluon
cache directory.
Rather than having the services subscribe to each individual event type,
have only one subscriber for the whole event object. This spreads the
logic to the service through the `EventHandler` type.
This is important for the next stage where the IMAP service will be
required to apply events from the past.
This patch adds the User Event Service which is meant to replace the
current event polling flow.
Each user interested in receiving events should register a new
subscriber using the `Service.Subscribe` function and then react on
the incoming events.
The current patch does not hook this up Bridge user as there are no
existing consumers, but it does provide extensive testing for the
expected behavior.
