Instrument Solid Queue

[fallwith]

We should instrument Solid Queue as its own concept in addition to the underlying database and Active Support Instrumentation pieces we already report on.

37 Signals' Solid Queue uses Active Job and a SQL database supported by Active Record while eschewing NoSQL stores.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-238741

[kaylareopelle]

PR to follow: rails/solid_queue#208

[kaylareopelle]

Instrumentation has been merged into Solid Queue: rails/solid_queue#208

It leverages ActiveSupport::Notifications.

[fallwith]

Rails 8 milestone issue: rails/rails#50442