Support rootfs subcommand

[bgoareguer]

Description

Related issues

• Close Support rootfs sub-command #793

Checklist

• I've read the guidelines for contributing to this repository.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[chen-keinan]

@bgoareguer thank you for this contribution.
I wonder, rootfs and fs works exactly the same, setting , env variables, scan packages on fs and command syntax.
the only different is the subcommand rootfs vs fs would it make sense to reuse the fs code and just replace the sub command based on helm values, wdyt?

[chen-keinan]

LGTM 🚀