- scripts/utils.sh is borrowed from software-layer. it includes various functions
  to be used with other scripts in this repo.
- scripts/cfg_files.sh is borrowed from software-layer. it provides functions to
  read a file that contains information about a job.
- changes to bot/build.sh:
  - added header, author, license
  - added assumptions
  - added set -e
  - source the above helper scripts
  - read job.cfg file
  - set core settings if needed: HTTP_PROXY, HTTPS_PROXY, LOCAL_TMP, LOAD_MODULES
  - expand LOCAL_TMP into STORAGE
  - load modules
  - obtain cpu_target_arch from job.cfg setting
  - bump eessi_version to 2023.04
  - calling install_compatibility_layer.sh: remove fixed local container, add
    storage option

- add arguments for resuming, retaining tmp and more verbose output
- extended and reformatted usage information
- source helper script scripts/utils.sh
- add support to resume a previous run given its temporary directory
- determine container runtime (singularity or apptainer)
- define env vars for both singularity and apptainer
- unset PKG_CONFIG_PATH before running ansible script
- only tar temporary directory if --retain-tmp option is given
- add message for how to resume a previous run

…remove them

…all if list not empty)

…rapping tasks (because pipefail is needed)

…efault)

- added some debugging
- remove any existing virtualenv
- make sure ReFrame is installed
- left some more example debugging (could be cleaned up)

added

```ansible
  vars:
   ansible_python_interpreter: "{{ gentoo_prefix_path }}/usr/bin/python3"
```

to all tasks using communit.general.portage