feat: cross-compatibility importation

[D-Nice]

Would need stateful credentails #4

Research if this would help customer acquisition... Ideally, a user rebuilds all their passwords utilizing SrsPass, and maybe what would make more sense is a script to help change some common accounts instead.

Likewise, research if export to another common pass format, might help decrease any feeling of a potential sunken cost with SrsPass if it doesn't fit them, thereby increasing market penetration.