Disable default redirect of DNSLink websites if it breaks Origin

[lidel]

Extracted from parent issue: #667, read it for full context.

[..] with latest Beta (v2.7.5.762) we have almost all the pieces of the UX for ( B ):

• It enables people to opt-out from redirects per hostname. (Per-site Redirect Opt-out #687)
• It shows IPFS actions on DNSLink websites even when redirect is disabled (Show IPFS Actions on DNSLink Sites #694)

What is missing: in case of DNSLink websites, we want to tweak this behaviour and disable redirect of DNSLink websites by default. People will still be able to opt-in via toggle introduced in (#687) and a global one in Preferences new menu item if they choose to do so, but the default should not change the Origin.

This will also solve the problem of websites hanging on initial load due to IPNS being slow ;-)

[lidel]

Note to self:

• What if we disable redirect of the root document only (URL in location bar)? Everything loaded as a subresource would still be redirected to IPFS.
  • This may break some pages due CSP, and may degrade browsing experience due to discrepancy between root and subresource load speeds

[lidel]

After chats with @autonome, @hugomrdias and @cwaring we decided to bump the priority of this.

Implementation notes:

• If HTTP server backing DNSLink website goes down, IPFS Companion will recover in a new tab automatically (Recover from dead Public Gateways #640, feat: recover from failed HTTP requests to third party gateways #783, feat: recover from DNS failures, support DNSLink for .eth #797)
  • This already implemented, noting it here is to emphasize there is no regression for offline and censorship scenarios
• There will be a new menu item for users who choose to break origin separation and load from local gateway.
  • It would open website from local gateway in a new tab to indicate origin change
  • In short, opt-in instead of opt-out, to respect Origin-based isolation and help with Host beta on IPFS ipfs-inactive/docs#271
• IPFS context actions will continue to be available on DNSLink websites