.arcconfig

rawdata: register the method for `ifiledata`

The interface have a `revision(..., raw=False)` method so it should get a
`rawdata` one. I am not sure why nothing complained about the lack of it
earlier.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}