Cargo is now started as a systemd user-level service whenever a
job requests for an ad-hoc storage service.

The following scripts have been added:

- `cargo@.service`: The Cargo systemd service file. Installed in
  `$SYSTEMD_UNIT_DIRECTORY` for user-level services (typically
  `/usr/lib/systemd/user/`)
- `cargoctl`: Control script for the Cargo user-level service. Installed
  in `$CMAKE_INSTALL_DATADIR/scord/cargoctl` (typically `/usr/share/scord`).
  Used internally by `cargo@.service`.

The `scord_prolog.sh` and `scord_epilog.sh` scripts have been updated to use
the new scripts when configuring the environment for a job.

Resolve "Rename `internal::job_info` and `internal:::adhoc_storage_info`"

Closes #154

See merge request !115

- Rename `job_info` to `job_metadata`
- Rename `adhoc_storage_info` to `adhoc_storage_metadata`
- Rename `pfs_storage_info` to `pfs_storage_metadata`

Resolve "Update Spack recipe for `0.3.1` release"

Closes #151

See merge request !112

Resolve "0.3.1 release"

Closes #150

See merge request !111

Resolve "Spack tests fail due to missing `scord-ctl.conf`"

Closes #148

See merge request !109

- Include `plugins/adhoc_services.d/*.sh` into build artifacts.

Resolve "Update Spack recipe for `0.3.0` release"

Closes #149

See merge request !110

Resolve "Prepare 0.3.0 release"

Closes #147

See merge request !108

Resolve "Libraries should be licensed under the LGPL"

Closes #146

See merge request !107

Resolve "Reorganize `/etc` and `/share` folder"

Closes #137

See merge request !106

Add `compiled/share` to build artifacts

`scripts/runner.sh` now saves logs for the applications it tries to run and
prints them if they cannot be started.

Scripts for controlling ad-hoc storage services now reside in
`CMAKE_INSTALL_FULL_DATADIR/scord/adhoc_services.d`, typically
`/usr/share/scord/adhoc_services.d/`.

Resolve "Add Slurm CLI plugin"

Closes #134

See merge request !95

Rename CLI options

Also, move job registration into `scord` to `slurm_spank_user_init` so
that it works both in `srun` and `sbatch`/`salloc`.

- `plugins/slurm/scord_prolog.sh`: Prolog script. Starts `scord-ctl`
   server and sets up environment.
- `plugins/slurm/scord_epilog.sh`: Epilog script. Stops `scord-ctl`
   server and cleans up environment.
- `plugins/slurm/scord_common.sh`: Common code to prolog and epilog.