[FEAT] Add log format options for `genny` cmd

[barkhayot]

Changes:

• Supports logfmt, JSON and basic otel formats
• Made it easy to add new log formats with a unified interface.
• Added a --format flag to specify the log format (logfmt, json, otel).

Usage

$ humanlog genny --format json

[barkhayot]

Thanks for this PR :)

Something that's bad about the current genny command is that it generates mostly bullshit logs that are quite unrealistic. Real logs have a lot more repetition in them and aren't as random as what genny makes right now.

So this change is interesting in that it brings more regularity to the logs. However as it stands, it removes too much randomness and makes the generated logs too simple and easy to handle. It's important to support generating logs of the type humanlog can't necessarily handle, along with logs that it does support.

If this change can be made so that it produces logs with sufficient complexity to keep humanlog honest, it'll be a good addition.

Thanks for the feedback! I’ll refine this to balance realism and complexity and share an update soon.