Make Hello packets include rate limit data

[apacheli]

Description
Add fields to the hello packet to include data about rate limiting similar to the HTTP API.

Why This is Needed
Currently, there is only a small part of the documentation that mentions anything about gateway rate limiting, and it's not mentioned under the Rate Limit topic either. Hardcoding values is generally not great, so knowing what they are initially can be very helpful.

Alternatives Considered

Additional Details
We could potentially receive another event telling us that rate limits have changed, so we could update during an active connection.

[imSanko]

I wanna work on to this project can you assign it to me.