pin-shortcut: Tracks hotseat states and adds unpin option for taskbar

This cl adds the unpin option by tracking the hotseat/taskbar state. The
option shown is determined by the following conditions:

1. If the target non-predicted item is on the taskbar, shows
   "Unpin from taskbar"
2. If the taskbar is not full, that is, reaching the limit of the
   available spaces, and the target item is anywhere outside of the
   taskbar, including All apps, shows "Pin to taskbar".
3. If the taskbar is full, simply don't show any shortcut option.

This cl also removes the option that will be shown on Launcher
homescreen or hotseat, as further UX alignment is needed.

One note about why the pin shortcut is not implemented in the
getShortcuts(). The reason is that getShortcuts does not have the
ItemInfo of the triggered item, while the SystemShortcut.Factory doesn't
have the hotseat/taskbar information. The simplest way at this point is
to check all the conditions in the controller and then manually add the
shortcut into the list.

Bug: 375648361
Test: Manual, Recording uploaded to buganizer
Flag: com.android.launcher3.enable_pinning_app_with_context_menu
Change-Id: I7d048bcb1b00f78651e909fbfcd911052a4cd4ef