fix(gateway): question marks in url.Path when redirecting

[hacdias]

Fixes ipfs/kubo#9882, fixes ipfs/ipfs-companion#1201. I updated toSubdomainURL to use the url.URL struct from Go to build the final URL. The problem was that rest was the original, decoded, r.URL.Path and it contains a ?. When Go parses it, it'd consider it as a query element, rightly so.

Kubo PR: ipfs/kubo#9894

[codecov]

Codecov Report

Merging #313 (77afd71) into main (1464d19) will decrease coverage by 0.50%.
The diff coverage is 78.57%.

@@            Coverage Diff             @@
##             main     #313      +/-   ##
==========================================
- Coverage   50.62%   50.13%   -0.50%     
==========================================
  Files         280      280              
  Lines       33724    33714      -10     
==========================================
- Hits        17074    16901     -173     
- Misses      14870    15029     +159     
- Partials     1780     1784       +4     

Impacted Files	Coverage Δ
gateway/hostname.go	68.01% <78.57%> (+0.73%)	⬆️

... and 17 files with indirect coverage changes

[lidel]

I've tested this in Kubo (ipfs/kubo#9894) and works as expected.
I've resolved conflicts in 77afd71 and tested again locally, still good.

Merging, to bubble up to ipfs/kubo#9894.
@hacdias please see my comment there for next steps 🙏