Split rate limitting between calibnet and mainnet

[LesnyRumcajs]

Summary

At the moment, there is a single rate limiter for both faucets. This means:

• we cannot change drip time selectively, e.g., higher one for mainnet, lower for calibnet,
• while the rate limiter blocks one, the other is also blocked.

Split the rate limiter into two, keeping in mind there might be more, and make the drip time configurable for faucets.

Completion Criteria

• Each network faucet drip time can be configured separately,
• Each network faucet is independent (rate-limit-wise) from the other.

Additional Links & Resources

I had to increase the drip time to 10 minutes in #137, but I would prefer to do it only for the mainnet.