feat: make routers optional and enable local insecure gateways

[2color]

Added by this PR:

• Ability to disable delegated routing using a toggle. When disabled, the routers configuration will not be passed to Helia.
• Probe for local gateway and add the local gateway to the configuration if available. If unavailable, remove the local gateway from the configuration.

Fixes #299 #288

Notes & open questions

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works

[lidel]

Did not run it locally yet, but dropping quick feedback / questions in the meantime.

[2color]

I'm currently blocked by a bug I found, where verifiedFetch does not respect the allowInsecure and allowLocal config options passed to it.

I have a reproduction here: https://codepen.io/2color/pen/VwOXeMz. But I haven't been able to find out where the root of the problem is. Still digging into this.

[lidel]

We don't have testing in place for this, so each flow needs to be inspected manually.
I did some testing in vanilla Google Chrome (empty profile each time) and both need a bit more polish.

• Localhost detection works only when dancing a specific way:
  • 🟢 Works when visiting the main domain first (http://test1.localhost:3000/) and then manually open config detects and prepends my localhost:8080 gateway, and uses it just fine
  • 🚧 Does not work when visiting the main domain first with config URL opened (http://test2.localhost:3000/#/ipfs-sw-config)
  • 🚧 Does not work if I visit subdomain first (http://specs-ipfs-tech.ipns.test3.localhost:3000/ does not prepend localhost)
  • ⭕ The detection does dot work in Brave because they have very strick adblock (Brave Shields) rules:

    
    Due to this, a big chunk of audience won't be able to benefit from this anyway 😞

• Disabling delegated routing works, but does more harm than good, making it not useful:
  • 🚧 Disabling delegated routing breaks DNSLink resolution (example), while it should only impact IPNS and not DNSLink

---

Between localhost detection and adjusting things in https://github.com/ipshipyard/waterworks-infra/issues/55 the latter improves things in all browsers, so we may want to park this and focus on that + the other quality-of-life improvements from the Camp milestone.

I feel we will get back to this once we simplify codebase after Camp. Right now, too much of a time sink.

[SgtPooki]

@2color I created #403 to replace this one. Closing