Tests @override-content-types is correctly implemented.
Test ab-override-content-types-021.xml is expected to pass.
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" name="pipeline" version="3.0">
   <p:output port="result">
   <p:unarchive include-filter="^ab-doc\.xml$" override-content-types="[['\.xml$', 'application/test+xml']]">
      <p:with-input href="../documents/ab-doc.zip">
   </p:unarchive>
   <p:identity>
      <p:with-input>
         <result>{p:document-property(., 'content-type')}</result>
      </p:with-input>
   </p:identity>
</p:declare-step>
<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
   <s:ns prefix="c" uri="http://www.w3.org/ns/xproc-step">
   <s:pattern>
      <s:rule context="/">
         <s:assert test="result">The root element is not 'result'.</s:assert>
         <s:assert test="result/text()='application/test+xml'">Text content of 'result' is not 'application/test+xml'.</s:assert>
      </s:rule>
   </s:pattern>
</s:schema>
Added attribute 'queryBinding' to schematron's schema.
Initial tests for override-content-types