Pass a unique identifier for the remote toolbar menu item

The MenuItem itemId is not guaranteed to be unique. For example custom
text processors are assigned Menu.NONE by android.widget.Editor.
Locallay implemented toolbar doesn't need this since it can rely on
using the same reference so we only need this for IPC.

We also fix issues with synchronization of what the local and remote
indend the toolbar to consist of, including process death.

Test: Manual
Bug: 363318732
Flag: android.permission.flags.system_selection_toolbar_enabled
Change-Id: I1bd0f329bef676955747d2df806e57b1b9972fe9