FS: support symlinks

[danimesq]

Checklist

• My issue is specific & actionable.
• I am not suggesting a protocol enhancement.
• I have searched on the issue tracker for my issue.

Description

It returns resolve error when, for example, accessing a index.html that is a symlink.

[Jorropo]

@danimesq can you add reproduction steps please ?

[danimesq]

@Jorropo for example, look at this site:

https://danimesq.eth.link/tokens/

Now compare with its page:

https://danimesq.eth.link/tokens/dani/

You'll notice the subfolder page is broken compared to its root page.
It's because it uses symlinks.

One of the broken files: https://danimesq.eth.link/tokens/dani/js/owl.carousel.min.js (shows ipfs resolve -r /ipns/danimesq.eth/tokens/dani/js/owl.carousel.min.js: no link named "js" under QmcBJQ9FMJJYBKPqYGqFX8N6vjiVSzqwtcHQVz5y52vt65)

See the live symlink here: https://github.com/danimesq/danimesq.github.io/blob/main/tokens/dani/js

Back in early 2021 I was here reporting issues with accessing a .git folder and seems like it was fixed; now it is the symlink issue that is bugging me

[lidel]

To unblock this, we need to specify how symlinks are supposed to work in IPFS and Gateway – filled ipfs/specs#368

[aschmahmann]

removing blocked label because it keeps showing up in our triage board. This issue is linked to the specs one so if someone is interested in pushing on this that's the place to start.