[iOS] Improve Voice Control name on settings

This demonstrates the use of accessibilityUserInputLabels.

Before, the default Voice Control name for one of the settings rows
was both the setting name and the value (e.g. "Search Engine Google").
This is because the default name comes from the text in the cell. Now,
the name is manually set to just the type of setting (e.g. "Search
Engine"), which is a better experience.

Bug: 1004319
Change-Id: Ie79a5bba46f8c6b688f1a31be20ef802875a2a4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1806462
Commit-Queue: Robbie Gibson <rkgibson@google.com>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697168}

ios/chrome/browser/ui/table_view/cells/table_view_detail_icon_item.mm

@@ -293,4 +293,8 @@ const CGFloat kCellLabelsWidthProportion = 3.0f;
   return self.detailTextLabel.text;
 }
 
+- (NSArray<NSString*>*)accessibilityUserInputLabels {
+  return @[ self.textLabel.text ];
+}
+
 @end