Create a `charon test mev` command to check the performance and connectivity of MEV relays

🎯 Problem to be solved

We need a way to initially check the performance and connectivity of MEV relays for DV setups to help prevent issues with block production.

[x] Create a charon test mev command
[x] Implement an initial check for fast connection to MEV relays
[x] Add the ability to measure basic response times from relays
[x] Include this test in the charon setup process
[x] Provide clear feedback to users about their MEV relay setup quality
[x] Add documentation explaining the limitations of this test (e.g., performance may vary over time, which could also be related to general mev relay overload)