collapse Take Snapshot button and TabBar to single row

Summary:
Problem: The take store snapshot and copy content buttons are in its own row, but take too much vertical space that could be used to show more record information.

Proposal: move them to the same row as te rest of the tab bars.

Reviewed By: tyao1

Differential Revision: D59659890

fbshipit-source-id: 147e3e13e99fc37a0ee2ec0b6caafe32be3c36a3

src/devtools/views/StoreInspector/StoreInspector.js

@@ -277,8 +277,6 @@ export default function StoreInspector(props: {|
           <ButtonIcon type="copy" />
         </Button>
         <div className={styles.Spacer} />
-      </div>
-      <div className={styles.TabBar}>
         <div className={styles.Spacer} />
         <TabBar
           tabID={tab.id}