Migrate: Transform glosslist into variablelist

[tomschr]

Problem description

@chabowski reported, that a glosslist is not correctly transformed and leads to a validation error in Novdoc. In Novdoc, there is no glosslist, only glossary.

Expected behavior

A list like this:

<glosslist>
   <title>Glossary as List</title>
   <glossentry>
    <glossterm>XML</glossterm>
    <glossdef>
     <para>The eXtensible Markup language</para>
    </glossdef>
   </glossentry>
  </glosslist>

should be converted to this:

<variablelist>
   <title>Glossary as List</title>
   <varlistentry>
     <term>XML</term>
     <listitem>
      <para>The eXtensible Markup language</para>
     </listitem>
   </varlistentry>
</variablelist>

Steps to reproduce the behavior

Create a glosslist and try to build a Novdoc document.