Back out "Back out Electron 7.1.1/7.1.2 upgrades"

Summary:
Original commit changeset: 05d13aca7145

Attempt to upgrade `electron` as it instacrashed; `electron-builder` version 22.1.0 didn't sign package correctly and caused the instacrash,

Reduced the version to 21.2.0 (latest).

Reviewed By: passy, nikoant

Differential Revision: D18954671

fbshipit-source-id: bc2dbd4fec9afb51d9a535974651b13d195407b4

src/chrome/settings/configFields.tsx

@@ -7,6 +7,7 @@
  * @format
  */
 
+import electron from 'electron';
 import {FlexColumn, styled, Text, FlexRow, Input, colors, Glyph} from 'flipper';
 import React, {useState} from 'react';
 import {promises as fs} from 'fs';
@@ -87,16 +88,18 @@ export function FilePathConfigField(props: {
       />
       <FlexColumn
         onClick={() =>
-          remote.dialog.showOpenDialog(
-            {
+          remote.dialog
+            .showOpenDialog({
               properties: ['openDirectory', 'showHiddenFiles'],
               defaultPath: path.resolve('/'),
-            },
-            (paths: Array<string> | undefined) => {
-              paths && setValue(paths[0]);
-              paths && props.onChange(paths[0]);
-            },
-          )
+            })
+            .then((result: electron.SaveDialogReturnValue) => {
+              if (result.filePath) {
+                const path: string = result.filePath.toString();
+                setValue(path);
+                props.onChange(path);
+              }
+            })
         }>
         <CenteredGlyph name="dots-3-circle" variant="outline" />
       </FlexColumn>