Integration with ipfs-share-files

[lidel]

Part of UX improvements for sharing local files (#342)

Shipping ipfs-share-files with Companion did not happen for two reasons:

1. We had to stop bundling Web UI due to reproducibility issues, and for the same reason Share app won’t be bundled any time soon.
2. ipfs-share-files itself requires some improvements around content discovery speed (at infra, websockets, webrtc), which did not land yet

I think we will switch approach and instead of opening uploaded resource at the gateway, display "success screen" with direct link to the gateway and “get share link” option that copies link to share.ipfs.io. This would also address #423.

[lidel]

No longer relefant: after successful import we open resource in Web UI (#810) and link is automatically copied to clipboard, removing the need for ipfs-companion-specific UI.

If ipfs-share-files gets picked up again, we could use its URLs for shareable links, but for now this can be closed.