byteify-strings: add test for byteify-strings.py This tests the basic features expected from this script, some cases may not be covered yet. A future patch will demonstrate an issue with multi-line `(`, `[` and `{` alignment and propose a fix.

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