Add the pop-out to companion window functionality from the window sidebar panel.

__tests__/src/actions/window.test.js

__tests__/src/components/CompanionWindow.test.js

__tests__/src/components/WindowSideBarPanel.test.js

__tests__/src/reducers/windows.test.js

__tests__/src/selectors/index.test.js

locales/en/translation.json

src/components/CompanionWindow.js

src/components/WindowMiddleContent.js

src/components/WindowSideBarPanel.js

src/containers/CompanionWindow.js

src/containers/WindowSideBarPanel.js

src/state/actions/action-types.js

src/state/actions/window.js

src/state/reducers/windows.js

src/state/selectors/index.js

src/styles/index.scss