[FEATURE] Expose wadm-internal events on a new stream

[protochron]

Right now the wadm_events stream is defined as a WorkQueue which is great for controlling what Wadm works on but is far less useful for external consumers of wadm. This is because you can only ever have a single consumer for any WorkQueue!

The issue here is that the wadm_events stream is the only place where manifest deploy and undeploy events are logged, so without polling for updates there is not a great way to be able to subscribe for only those events. An alternative which I'm pursuing is creating a stream mirror of the wadm_events stream so that I can create a new consumer so that the wasmcloud-operator can take actions whenever a new manifest is deployed or one is undeployed.

With the new features in NATS 2.10 (similar to #81), we can be much smarter in how we create new consumers and expose a stream for downstream consumers. What I'd like to do is:

• keep relaying the existing notifications to wadm_events for now.
• relay all deploy and undeploy notifications to a new stream (wadm_scheduler_events? Not sure of a good name yet). The stream's subject should be something like wadm_scheduler_events.>, and wadm should add the deploy and undeploy notifications on their own prefixed subjects, ex. wadm_scheduler_events.$lattice_id.manifest_deployed and wadm_scheduler_events.$lattice_id.manifest_undeployed. Doing so would allow consumers of the stream to only subscribe to only events they are interested on particular lattices or even only for specific events without needing to parse a CloudEvent and check the payload for the event type before deciding on what to process. This should not be a work queue and should instead be a stream with sensible limits. Downstream consumers can then mirror the stream into a work queue or anything else they want and build out consumers on that stream.
• Eventually remove the manifest deployed and undeployed events from the wadm_events stream and use a different work queue to provide the same functionality. This work might overlap with Remove mirror stream on update to NATS 2.10 #81 since we wouldn't necessarily need one main mirror stream to drive all work in wadm.