Implement file handling in terms of io.FS and os.Root

Eschewed features

• This issue is not requesting templating, unstuctured edits, build-time side-effects from args or env vars, or any other eschewed feature.

What would you like to have added?

Go 1.24 added its own filesystem re-rooting capability with os.Root.

While this was primarily intended as an anti-traversal mechanism, the API essentially allows for designating any arbitrary folder as a new filesystem root... including things like temp directories. This, in combination with (readonly capabilities of) io.FS, allows for a more standardized way to interact with the filesystem.

It would be great to migrate all file handling to use these packages/interfaces.

Why is this needed?

Use of io.FS and os.Root would allow for easier integration with downstream consumers and libraries. Additionally, it could eventually eliminate a large maintenance burden in a critical security area, by delegating traversal prevention to the standard library.

Can you accomplish the motivating task without this feature, and if so, how?

While it's generally possible to implement a wrapper to go from kyaml.filesys -> io.FS (given the opposite may be the best migration/re-implementation path), this would be large surface area for each consumer to implement. Alternatively, consumers are forced to rely on navigating through the underlying physical filesystem instead of a common interfacing type.

What other solutions have you considered?

N/A.

Anything else we should know?

No response

Feature ownership

• I am interested in contributing this feature myself!