feat: add complex xquery support

[TinkoLiu]

Added support for complex XQuery usage.

e.g.

An XML from Ross Dashboard

<?xml version="1.1" encoding="UTF-8"?>
<card autosave="true" online="true" slot="1"
     sourceframename="Frame"
     status="0" statustext="OK" version="2.0">
     <params>
          <param access="1" maxlength="0" name="CountdownValue" oid="1"
               type="STRING" value="00:00" widget="label"/>
          <param access="1" constrainttype="INT_NULL" name="TargetTime"
               oid="2" precision="0" strvalue="0" type="INT32" value="0" widget="default"/>
          <param access="1" maxlength="0" name="CountdownToTarget"
               oid="3" type="STRING" value="936:33" widget="label"/>
          <param access="1" maxlength="0" name="DateTime" oid="1001"
               type="STRING" value="2023-09-29 02:23:26" widget="label"/>
          <param access="1" constrainttype="INT_NULL"
               name="InputCountdown" oid="4" precision="0"
               strvalue="181" type="INT32" value="181" widget="default"/>
          <param access="1" constrainttype="INT_NULL"
               name="InputTargetHout" oid="5" precision="0"
               strvalue="20" type="INT32" value="20" widget="default"/>
          <param access="1" constrainttype="INT_NULL"
               name="InputTargetMinute" oid="6" precision="0"
               strvalue="38" type="INT32" value="38" widget="default"/>
          <param access="1" constrainttype="INT_NULL"
               name="InputTargetSecond" oid="7" precision="0"
               strvalue="0" type="INT32" value="0" widget="default"/>
     </params>
     <statsmenu menuid="0" name="status"/>
     <configmenu menuid="1" name="config"/>
</card>

With XQuery str //param[@oid=3]/@value will get the result like

Other XQuery methods such as sum or count is also available

[royshil]

this checks out! Thank you so much for this contribution!