Add SNSS parser

[Onager]

Add a (possibly plugin-based) parser for Chrome SNSS-formatted files (Current session, last tabs etc.).

Existing work: https://github.com/JRBANCEL/Chromagnon/wiki/Reverse-Engineering-SNSS-Format https://github.com/deactivated/python-snss

[sydp]

https://source.chromium.org/chromium/chromium/src/+/master:components/sessions/core/