Canonicalize URL used as db index key

[ivilata]

Currently we lack a canonical format for URLs used as keys. For instance, one browser may request http://foo.bar/foo-bar and another one http://foo.bar/foo%2dbar, which are the same URL, but since we don't try to put them in a single format, they would get injected under two different keys.

This applies both to IPFS and BEP44.