Making the parseAndAddDeepShortcut api private.

There is no need to expose this api. Missed the comment https://googleplex-android-review.git.corp.google.com/c/platform/packages/apps/Launcher3/+/17956680/comments/1c9b7443_cc54296d

Test: Tested manually on device.
Change-Id: If71e203f32a59fa59c406303411a37cba7b6c62e
1 file changed