tests/test-pull-permission.t

rust: move rustfmt.toml to repo root so it can be used by `hg fix`

`hg fix` runs the formatters from the repo root so it doesn't pick up
the `rustfmt.toml` configs we had in each the `hg-core`, `hg-cpython`,
and `rhg` packages, which resulted in warnings about `async fn` not
existing in Rust 2015. This patch moves the `rustfmt.toml` file to the
root so `hg fix` will use it.

By putting the `rustfmt.toml` file in a higher-level directory, it
also applies to the `chg` and `hgcli` packages. That makes
`test-check-rust-format.t` fail, so this patch also applies the new
formatting rules to those packages.

Differential Revision: https://phab.mercurial-scm.org/D9142

#require unix-permissions no-root

  $ hg init a
  $ cd a
  $ echo foo > b
  $ hg add b
  $ hg ci -m "b"

  $ chmod -w .hg/store

  $ cd ..

  $ hg clone a b
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 97310831fa1a
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ chmod +w a/.hg/store # let test clean up

  $ cd b
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files

  $ cd ..