pin-shortcut: Add pin shortcut to the context menu

This cl adds the pin shortcut option to the context menu, where
it works on Home launcher, hotseat, and pinned apps on the
taskbar.
Currently the option is a no-op.

Bug: 375648361
Test: Manual. Recording uploaded to buganizer
Flag: com.android.launcher3.enable_pinning_app_with_context_menu
Change-Id: I5d1284a6e909fd75f14e81c3ae713da3cdc01ce3