Fix ArgumentError when importing netsparker xml
Clear state for new vulns

[FixRM #7665]
Add actual cdata handler

Netsparker puts requests, responses, and info for vulns inside a cdata
(which makes sense because it's usually html snippets). This commit
handles that so report_web_vuln will actually be somewhat useful. Note
that the request is ignored by report_web_vuln despite there being a
place for it in the WebVuln model.

[SeeRM #7665]
Merge branch 'bug/rm7665-netsparker-import' of github.com:jlee-r7/metasploit-framework into jlee-r7-bug/rm7665-netsparker-import
Merge branch 'bug/rm7665-netsparker-import' of github.com:jlee-r7/metasploit-framework into jlee-r7-bug/rm7665-netsparker-import