diffutil: move the module out of utils package
mercurial.utils modules inherit the property of the mercurial.util, which is
no dependency on ui, repo, ctx, etc. As the diffutil module seems to reside
in the scmutil layer, it's probably better to not put it under the utils
package.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}