remove splits

Individual splits can now be removed for an application. The
application will be terminated if it's running when a split is
removed.

To remove a split, either use either "uninstall":
    $ adb shell cmd package uninstall <PACKAGE> <SPLIT>

or "install-remove":
    $ adb shell cmd package install-create -r -p <PACKAGE>
    $ adb shell cmd package install-remove <SESSION> <SPLIT>
    $ adb shell cmd package install-commit <SESSION>

For "install-remove" you must use '-r' and '-p' when creating
the session.

Bug: 27547051
Change-Id: I4d71a19ad45e39f6622d9ab6791ea8c4230a79e0