history panel store

[josephfusco]

The goal here is to have a Redux store registered that maintains the state of the history panel and allows 3rd party code to see what's in the state and write back to the state.

The history panel uses the Redux store.

Acceptance Criteria

• baseline tests before refactoring (i.e. item can be added/removed from history, opened in document editor from history)
• pull request showing tests for existing functionality passing
• pull request showing tests still passing for refactored code (include new tests as needed)

Possible Public State

• addToHistory
• editLabel
• items
• toggleFavorite
• deleteFromHistory
• setActive

Related

• Add a button to the "Activity Bar Panel" #110
• https://github.com/wp-graphql/wpgraphql-ide/pull/78/files#diff-68cfdabf9fa2ce99fa19fdbe25785f2622056c22f88b1f846d3ac7ffffea0744