Move Gitlab::SidekiqMonitor to namespace Gitlab::SidekiqDaemon::Monitor
- Class name and file name change
- File path change to lib/gitlab/sidekiq_daemon/monitor.rb
- Update class usage/reference in other files, including documentation
This makes:
- very shallow `Middleware::Monitor` to only request tracking
of sidekiq jobs,
- `SidekiqStatus::Monitor` to be responsible to maintain persistent
connection to receive messages,
- `SidekiqStatus::Monitor` to always use structured logging
and instance variables
