Fix QPL layout regeression

Summary:
Fixed the layout usage in QPL, the `horizontal` was correct, but the elements where swapped (the table was supposed to take all remaining size, and sidebar it's needed space, rather than the reverse).

Made this more explicit in the Layout component, by splitting it up in `Layout.(Top|Left|Right|Bottom)`, so that one has to make an explicit choice here, making it less error prone.

Reviewed By: passy

Differential Revision: D21572438

fbshipit-source-id: 29aa3462a3c96d048825be3157730e26182cb2fa

desktop/app/src/ui/components/searchable/Searchable.tsx

@@ -472,7 +472,7 @@ const Searchable = (
     render() {
       const {placeholder, actions, ...props} = this.props;
       return (
-        <Layout>
+        <Layout.Top>
           <SearchBar position="top" key="searchbar">
             <SearchBox tabIndex={-1}>
               <SearchIcon
@@ -540,7 +540,7 @@ const Searchable = (
             bodySearchEnabled={this.state.bodySearchEnabled}
             filters={this.state.filters}
           />
-        </Layout>
+        </Layout.Top>
       );
     }
   };