refactor: add composite fs for post-analyzers

[knqyf263]

Description

Add composite filesystem for post-analyzers so that artifacts can share the fs implementation.

Related PRs

• fix(vm): support post analyzer for vm command #4544

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• 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).

[masahiro331]

🚀 LGTM🚀