Add Generic Parser Strategy for Accordian Layout

[aep7128]

Generic Parser design here: https://app.diagrams.net/#G1ZhVaJu0XKpyKtDhr2uqTQVVWg-X07XC1

Generic Parser will use this strategy if it finds a source with an accordian layout
(ex. Available Critical and Security Updates for NI Software
https://openvpn.net/security-advisories/
https://www.pega.com/trust/security-bulletins
https://www.asus.com/content/asus-product-security-advisory)

[aep7128]

More details on this use case here: https://docs.google.com/spreadsheets/d/1MHsXLgoQIi4hQg4aM6Q23XBEUulTRReZlxNw4vpeS70/edit#gid=517593048