Enable Pinning Deep Shortcuts in Secondary Display

Currently, deep shortcuts can be pinned to the workspace grid (home screen) upon long click of the icon. However, a challenge in doing so has been persistence of these shortcuts because whenever a new secondary display activity gets started, these pinned shortcut icons vanish. To address this, we store pinned shortcut data in memory which is done here via SharedPreferences.

Retrieval of this data still needs to be done as outlined here: https://docs.google.com/document/d/1wLb2h8qCPGur-VsufCH4mLnnuLDLcmMq0FrCo7ichu8/edit#heading=h.44bkbp2hiok0.

Bug: 241843710
Test: Manual
Change-Id: I709f046fac79fdfd47c3c84054173992d81757ae