And CPU bound and IO bound worker categories to the Beacon Processor

[eserilev]

Add CPU bound and IO bound worker categories to the beacon processor

• CPU bound workers: Cpu intensive tasks. We don't want to schedule to many of these at once or we might see degraded node performance
• IO bound workers: non cpu intensive tasks i.e. writes to disk, requests to a server. pretty much anything thats not cpu intensive. We could potentially schedule lots of these at once without degrading node performance

Theres also a very small refactor I made to move the WorkType and Work enum definition and impls to a separate file

TODO

• Add more description to this PR
• Make sure work events are correctly categorized to IO bound and CPU bound

Heres a short video where I go through the PR
https://www.youtube.com/watch?v=0TFjHoBFyms