Factor out GK fetch logic

Summary:
Removed loadGKs and loadDistilleryGKs from the `flipper` API, as it leaked implementation details of GK that didn't work well with decapitation later in this diff, and refactored it to using `getFlipperLib().GK`.

After that discovered that those APIs are actuallly only used by nt-shared's performGKcheck, which was already removed from all usages in D27736036, so just removed the code altogether. But left loading distillery GKs in place, since that is good infra structure to provide anyway(?), although we don't have active use cases atm

Reviewed By: jknoxville

Differential Revision: D32529600

fbshipit-source-id: a03fb14ada21018d329eea78a59f1b20610b2fd3

desktop/plugins/public/layout/index.tsx

@@ -16,7 +16,6 @@ import {
   Toolbar,
   DetailSidebar,
   Button,
-  GK,
   Idler,
   ReduxState,
   ArchivedDevice,
@@ -36,6 +35,7 @@ import {
   IDEType,
 } from 'flipper';
 import {message} from 'antd';
+import {getFlipperLib} from 'flipper-plugin';
 
 type State = {
   init: boolean;
@@ -463,7 +463,9 @@ export default class LayoutPlugin extends FlipperPlugin<
       </Sidebar>
     ) : null;
 
-    const showAnalyzeYogaPerformanceButton = GK.get('flipper_yogaperformance');
+    const showAnalyzeYogaPerformanceButton = getFlipperLib().GK(
+      'flipper_yogaperformance',
+    );
 
     if (!this.state.init) {
       return null;