feat: support ipns address translations

[hacdias]

Hi! 👋

This adds support for IPNS Links which are also part of IPFS spec. The address resolution is exactly the same since they're encoded the same way.

I needed to change the default ipfsGateway from ipfs.dweb.link to ipns.dweb.link which is similar to the defaults of IPFS Companion. I added a migration to replace whatever value the user has there by the new default.

This does not add support for DNSLink though. /cc @lidel

[lidel]

FYSA dweb.link is migrating from nginx to native subdomain support in go-ipfs 0.5, so we need to wait until migration is complete and *.ipns.dweb.link works.

Also, with go-ipfs 0.5 other gateway providers such as Infura are now able to run their own subdomain gateways, as described here.

[whymarrh]

One small suggestion

[whymarrh]

@lidel what does your comment mean for the timeline of this PR? Is that a follow-up change?

[lidel]

@whymarrh no follow-up is needed, but the feature introduced in this PR won't work until IPFS project updates its DNS to support hostnames under *.ipns.dweb.link (eg. https://bafzbeiaqarwnhp7vmqgkhfbqyf32qgkf65xluww5vr2xlang2rekfiquku.ipns.dweb.link).
It should be fixed soon, will post when ready.

[whymarrh]

Sounds good, thanks

[lidel]

@hacdias I believe IPNS support is ready:

https://dweb.link/ipns/QmPRB9SNEfYaTaZ88VLCpddTYD45B53sC8yH8xYZXGPLJp
is now upgraded to case-insensitive identifier and redirected to own Origin:
https://bafzbeiaqarwnhp7vmqgkhfbqyf32qgkf65xluww5vr2xlang2rekfiquku.ipns.dweb.link

[whymarrh]

Two small suggestions

[whymarrh]

LGTM, thanks @hacdias!

[whymarrh]

We're building up to a version 8 release in the next couple of weeks—this will be part of that