[CPP] Refactor IsRateLimitedPacket method to use milliseconds

[ampitere]

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What does this pull request do?

Updates PacketGuard.IsRateLimitedPacket to use milliseconds instead of seconds. Allows rate limiting to use fractions of a second. Resolves #430

Steps to test these changes

1. Login
2. Do some stuff
3. ???
4. Things don't break

[zach2good]

With this change, don't you also need to change the tikmintw) timings 20 or so lines above? Otherwise they're now rate limited to 2ms...

[ampitere]

With this change, don't you also need to change the tikmintw) timings 20 or so lines above? Otherwise they're now rate limited to 2ms...

Definitely needs to be updated for those yep, spamming jump looks pretty silly at 2.