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]

Codecov Report

All modified and coverable lines are covered by tests ✅

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

Additional details and impacted files

@@            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     

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[weiihann]

Closing this, additional flags are harder to maintain.