centralize DOR event log event creation, centralize dor-services-client config in boot.rb

[jmartin-sul]

FileWatcher should use Dor::TextExtraction::DorEventLogger to create DSA event log entries.

also, instead of calling Dor::Services::Client.configure multiple times, since it's a Singleton, we should only call it once, in boot.rb (closest thing the robots have to our typical usage of config/initializers in a full Rails app). Eventually that will be replaced by a call to dor-event-client when #1270 is resumed/done (should also be a single init in boot.rb, since Dor::Event::Client is also a Singleton).