Ability to export/import shared logs

[false-spring]

With the .gbfr log format, it should be possible to share these out and import them back into the parser for analysis.

[false-spring]

With https://github.com/false-spring/gbfr-logs/commit/ea22f2c691fec6581e5c0b5cc578ffadaccdfb74 it's possible to export the raw damage event log to CSV, which makes it possible to parse and reconstruct the timeline.

However, I plan to add additional meta information around the datetime, saving sigils / trait loadout per party chara, so will need to find a format that also saves it alongside the event log. I haven't decided on a format yet, but ideally an easy to use format that other developers can consume.