fileset: make debugfileset filter repository files
This prepares for the structural change of the fileset. A computed fileset
will no longer be a set of files, but a boolean function (i.e. matcher) to
test if an input file matches the given fileset expression.
--all-files option is added because some examples in the test need to scan
files across revisions.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}