Update SidebarInteractiveContainer Flex Parameter to Allow for Both Grow and Shrink

Summary:
- Per the title, we're explicitly setting the `flex-basis` to 0 and `flex-grow` and `flex-shrink` to 1.
- We've noticed that the `Sidebar` does not allow shrinking less than half the page when `flex-basis` is 1.
- With this change, we can now resize the `Sidebar` component without issue.
- ** We're taking this approach because the linter has issues with us using `styled` with `Sidebar` **

#nocancel

Differential Revision: D32477863

fbshipit-source-id: 99a50bc047d59add833c1fc113ab159c08767e05

desktop/flipper-plugin/src/ui/Sidebar.tsx

@@ -18,7 +18,7 @@ import {theme} from './theme';
 
 const SidebarInteractiveContainer = styled(Interactive)<InteractiveProps>({
   display: 'flex',
-  flex: 1,
+  flex: '0 1 1',
 });
 SidebarInteractiveContainer.displayName = 'Sidebar:SidebarInteractiveContainer';