Use logger channel service rather than factory

[paul-m]

Modifies the following services to use a logger channel service instead of using a logger factory service to make its own channel:

• dkan.datastore.event_subscriber
• json_form.builder
• json_form.schema_ui_handler
• datastore.reimport.commands

We also discover that some plugins generate their own logger channel objects rather than injecting existing ones.

• ImportQueueWorker
• LocalizeQueueWorker
• PostImportResourceProcessor
• HideCurrentRevisionAction

In addition, analysis reveals that dkan.metastore.event_subscriber doesn't actually use a logger at all, so we remove that dependency from the service declaration.

Modify tests to pass.

Minor CS changes.