Allow usage of multiple IPs for mojang requests

[wagpa]

May be helpful:

• https://stackoverflow.com/questions/45012233/how-to-bind-a-request-to-a-specific-network-interface-with-rust-hyper-http-clien
• https://stackoverflow.com/questions/62838100/how-to-get-rust-hyper-to-specify-outgoing-source-port

[wagpa]

We see three general options:

1. place load balancer / reverse proxy in front of xenos
2. in xenos, use something like a message queue
3. place proxy behind xenos

Option (1) is problematic in that it would not work nicely with sessions. It could be implemented using the healthy/ready status indicating that all mojang request token have been used up. Problematic with bursts.

Option (3) could be done, but contradicts the goal of xenos. Originally, xenos should ensure that requests could be made.

Option (2) would probably be the best feature wise. It could implement integrate request deduplication. But it probably comes at
high development costs.

Another Option (4) would be to keep sessions with multiple xenos instances in each client. But this would only work (nicely) inside the cluster. The clients wouldn't be able to synchonise usages and deduplicatuion wouldn't be used.

[scrayos]

To follow up on the "one node has multiple IPs that it can utilize": That should be possible with this: https://docs.rs/reqwest/latest/reqwest/struct.ClientBuilder.html#method.local_address

We can just specify the local address then.