.arcconfig

grep: enable all-files by default (BC)

This patch deprecates the `--all-files` flag and make the all-files
behaviour as default.

In test-grep.t, I removed '--all-files' from every command where it was
used, to reflect that all-files behaviour is default and there is no
change even after the removal.
And other changes in test files are because of changed behaviour.

Differential Revision: https://phab.mercurial-scm.org/D7000

.. bc::

    `hg grep` now searches working copy file contents by default. We
    recognize this is a significant change from past behavior, but
    surveys of large bodies of users indicated nobody used (and almost
    nobody understood) the previous no-flags behavior of `hg
    grep`. The new behavior aligns with the behavior most users
    expected (including hg's maintainers), which also happens to be
    the behavior of `git grep`. Given that the old behavior was
    confusing to the point of being unusable, we were comfortable
    changing this behavior.

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