Implement React Context API

- Move API GET request to /v2/config out to the top level of our App.
- Store /v2/config response data in sessionStorage.
- Use Context API to pass down relevant data to Organizations component.
- Wrap our AnsibleSelect component as a context consumer and pass in the list of Ansible Environments of the logged in user.
- Clear sessionStorage object when user logs out.
- Update unit tests.

src/context.jsx

@@ -0,0 +1,3 @@
+import React from "react";
+
+export const ConfigContext = React.createContext({});