Header component with account, org, and user actions

[juliajames12]

For the new multi-org experience, we want to allow users to select from their multiple organizations easily and always be able to see what account, org, and user profile they are in without having to click into the main menu.

We'll need a new global header component that includes the following:

• Two dropdowns with icon in between to indicate hierarchy
• User profile button with dropdown (I believe there is a user profile button in Clockface that we can just tweak to match the new experience and design system).

Design: https://www.figma.com/file/fvVSKwnepmRWvzFlIxCWCe/Multi-org?node-id=546%3A3057

[brandenTenbrink]

https://github.com/influxdata/clockface/pull/783

This PR will create the dropdown component for the header. The header will be built in the UI not clockface. Closing since this is now a non issue.