templatekw: make experimental {peerpaths} return a single-level dict (BC)
This was planned as in
c0d8de2724ce, "{peerpaths.default.pushurl} will be
translated to peerpaths['default'].makemap()['pushurl'], which means
{peerpaths} should be a single-level dict and sub-options should be
makemap()-ed."
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}