[Pipeline Viewer] Initial version follow-up work

[justinkambic]

Purpose

This issue tracks the follow-up work to the new Config View we're using to express Logstash configuration files in the Monitoring UI, merged in https://github.com/elastic/kibana/pull/18597.

• ~Additional work to refactor/remove unneeded code will follow this one. Breaking this work up is a conscious choice driven by a desire to segregate the scope of the changes. Tracked here: https://github.com/elastic/kibana/issues/19736 Open: https://github.com/elastic/kibana/pull/20122~
• We need to update the top-level nav, but it lives in Angular, so that will be a separate PR to Reactify that piece of the view, tracked here https://github.com/elastic/kibana/issues/18976
• The data the model classes give this view may end up changing, or we may need to modify the way the view behaves when displaying new pipelines, or dead pipelines https://github.com/elastic/kibana/issues/19429
• A proposed design element is the highlighting of nested statements, probably on a delayed hover. This would lower the opacity of outside statements. It's tracked here: https://github.com/elastic/kibana/issues/19463
• ~Refactor the CollapsibleStatement class to behave as a wrapper for props.children https://github.com/elastic/kibana/issues/19844 Open: https://github.com/elastic/kibana/pull/20252~
• ~Remove bare <img>s in favor of EuiIcons where possible https://github.com/elastic/kibana/issues/20021 Open: https://github.com/elastic/kibana/pull/20330~
• ~Add unit tests for Config View sub-components. Open: https://github.com/elastic/kibana/pull/20329~
• ~Rename Config Viewer to use Pipeline Viewer name https://github.com/elastic/kibana/issues/20123 Open: https://github.com/elastic/kibana/pull/20230~
• ~Fix typo in className prop https://github.com/elastic/kibana/pull/20104~

[chrisronline]

Removing monitoring so we can ensure our backlog is up to date. This work should be done by the logstash ui team