I ran into this error when trying to run `opendkim-genkey` in a vars
generator:
```console
=========================================================================== Command ===========================================================================
nix \
--extra-experimental-features 'nix-command flakes' \
shell \
--inputs-from /nix/store/9r3ddw80dz4qzci9pj57ppbh6gy2pgv9-clan-cli/lib/python3.12/site-packages/clan_cli/nixpkgs \
'nixpkgs#bash' \
'nixpkgs#bubblewrap' \
-c bwrap \
--unshare-all --tmpfs \
/ \
--ro-bind /nix/store \
/nix/store \
--dev /dev \
--bind /tmp/nix-shell.ClOjgJ/vars-kh4qrnas \
/tmp/nix-shell.ClOjgJ/vars-kh4qrnas \
--chdir / \
--bind /proc \
/proc \
--uid 1000 \
--gid 1000 \
-- bash \
-c /nix/store/p0089w4y1w3h535g7ipv4jl4r6mb2hs2-generator-dkim-playground.jflei.com.mail
=========================================================================== Stderr ============================================================================
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LC_CTYPE = (unset),
LC_NUMERIC = (unset),
LC_COLLATE = (unset),
LC_TIME = (unset),
LC_MESSAGES = (unset),
LC_MONETARY = (unset),
LC_ADDRESS = (unset),
LC_IDENTIFICATION = (unset),
LC_MEASUREMENT = (unset),
LC_PAPER = (unset),
LC_TELEPHONE = (unset),
LC_NAME = (unset),
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Can't exec "/bin/sh": No such file or directory at /nix/store/nfawbww80p1hgpymfgq1vq8wqlak75yh-opendkim-2.11.0-Beta2/sbin/.opendkim-genkey-wrapped line 139.
.opendkim-genkey-wrapped: openssl died with signal %d
127
Return Code: 1
1 hosts failed with an error. Check the logs above
```
As we allow `/bin/sh` in the nix build sandbox, I assume we're OK
allowing it here as well?
On macOS mktemp returns a temporary directory in a symlink.
Nix has a bug where it won't accept path:// located in a symlink.
This avoid this issue by always resolving symlinks as returned by
TemporaryDirectory.
Add dynamic completion scaffolding to the clan `cli`.
Also add a dynamic completion mechanism for machines for commands that
have machines as their sole argument.
More intricate dynamic completions will be implemented in follow up
PR's.
Add `--regenerate` flag to `clan facts generate` which allows forcing
the generation of facts, regardless of their current existence.
Examples:
```
clan facts generate [MACHINE] --regenerate
```
or
```
clan facts generate [MACHINE] --service [SERVICE] --regenerate
```
Add `--service` flag to the `clan` cli which allows specifying a certain
service to be generated.
Example:
```
clan facts generate [MACHINE] --service [SERVICE]
```
Fixes#1395
