cmd/juno: add --instance flag

[weiihann]

Description

This PR adds a new flag called --instance to initialize port numbers automatically based on the instance count. This flag affects the following ports:

• http-port
• grpc-port
• metrics-port
• pprof-port
• ws-port

Example

Each instance count will increment the default value of the respective ports by 10. For example:

The default value of each port is as follows:

• grpc-port = 6064
• http-port = 6060
• metrics-port = 9090
• pprof-port = 6062
• ws-port = 6061

Command: ./juno --instance 2 Then the ports would have the following numbers:

• grpc-port = 6074
• http-port = 6070
• metrics-port = 9100
• pprof-port = 6072
• ws-port = 6071

Rationale

This feature is useful for initializing multiple instances of Juno nodes, without having to care for the port conflict issues.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 75.40%. Comparing base (4e6dcd7) to head (3bb40da).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1905 +/- ## ========================================== - Coverage 75.43% 75.40% -0.04% ========================================== Files 97 97 Lines 8342 8355 +13 ========================================== + Hits 6293 6300 +7 - Misses 1519 1523 +4 - Partials 530 532 +2 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[weiihann]

Closing this, additional flags are harder to maintain.