Creates a new VPP assignment by ID

<vpp_assignment>
    <general>
        <name>Sample Assignment</name>
        <vpp_admin_account_id>1</vpp_admin_account_id>
    </general>
    <ios_apps>
        <ios_app>
            <adam_id>767319014</adam_id>
            <name>Angry Birds Epic RPG</name>
        </ios_app>
        <ios_app>
            <adam_id>923394341</adam_id>
            <name>Alien Blue for iPad - reddit official client</name>
        </ios_app>
    </ios_apps>
    <mac_apps/>
    <ebooks>
        <ebook>
            <adam_id>1058120411</adam_id>
            <name>Transforming Healthcare</name>
        </ebook>
    </ebooks>
    <scope>
        <all_jss_users>false</all_jss_users>
        <jss_users/>
        <jss_user_groups/>
        <limitations>
            <user_groups/>
        </limitations>
        <exclusions>
            <jss_users/>
            <user_groups/>
            <jss_user_groups/>
        </exclusions>
    </scope>
</vpp_assignment>