Docs Explorer Plugin

[jasonbahl]

Acceptance Criteria

The "Docs Explorer Panel" should be migrated to a "plugin", (similar to the Query Composer and Help Panel) making use of registerActivityBarPanel and using redux for state management.

The components needed for the Docs Explorer Panel should be coupled with the plugin (similar to the Query Composer).

We'll likely need to introduce some new redux abilities to support features like:

• visiting a link that loads the IDE with the Docs panel open to a specific Type (ie ?wpgraphql-ide&docs="AcfFieldGroup" would load the ide with the AcfFieldGroup Type already displayed in the panel) - implementation details not yet prescribed.
• command+clicking fields and types in the document editor opens the docs explorer currently, but not via redux. This needs to be redux-ified so other components can add the ability to control the state of the docs panel

---

related: #119