Add support for old accounts participating in suspect tests

[pyuk-bot]

https://www.smogon.com/forums/threads/an-alternate-suspect-test-procedure-that-lets-users-qualify-with-their-main-accounts.3756259/
This will need an accompanying PR to handle the server-side command to reset RD. It won't need a client PR unless sending both true w/l/t and suspect participation w/l/t data in ladderget is desired.

[pyuk-bot]

Darn, it didn't run unit tests. Please hold while I do that locally.

[pyuk-bot]

This implementation relies on start_date time codes for suspect tests being unique. They basically always are, but this doesn't include any error handling for what happens if there's a conflict for start_date, which will only happen if 2 tests are started in the same second. I tried to add error handling for that, but I ran into an issue where if an admin starts 2 tests at the same time by sending both commands at once in a multiline message, the second command failing would cause both commands to return an error, creating a desync between the showdown server and the loginserver's suspect files. Because of this problem, even if I did add error handling, the desync would still happen, so it wouldn't really fix anything. As far as I can tell, the only way to resolve such a desync is to edit one or both files manually. The bug causing this double error response is deep in some low-level stuff that I don't want to mess with. It should be fine to just not worry about it as long as everyone who's starting suspect tests knows not to start two at once.