Performance testing ICM message throughput

[geoff-vball]

We should measure the round-trip signing latency for avalanchego when using the cubist signer vs local key.

We should see if impacts overall ICM message singing throughput, or if other factors dominate.

We should also check what regions cubist hosts servers in to keep this in mind for global users.

[geoff-vball]

Latency for calls to cubist via the signer running locally were ~200-250ms