need to support a Filestore nocopy option

[ec1oud]

Kubo has FilestoreEnabled as an experimental option. I think not duplicating data (and not storing it in an obfuscated way, when I've already got the files that I want to share, and intend to keep them in the same place) is an obvious good idea: IMO it should no longer be experimental unless there are too many things that can go wrong. https://github.com/ipfs/kubo/blob/master/docs/experimental-features.md#ipfs-filestore says "Needs more people to use and report on how well it works"; but having API support for this would be a good way to get more people to use it.

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[Jorropo]

Filestore has corruptions issue if you modify / remove / move files that are still stored in filestore, it's probably not gonna get unexperimentalled at any time in favor of reflinking (same trick but done by the kernel with Copy-On-Write so no corruption possible).

We have two Kubo go api clients for history reasons, the other one have it afaik.
https://github.com/ipfs/go-ipfs-http-client

If you want to add it to this package I'll be happy to review it.