Create a jug_xl container with oneAPI support.

Modify .gitlab-ci.yml to add new containers.

Source setvars.sh from /etc/profile while using bash login shell.

Source setvars.sh while invoking bash login shell

make entrypoint.sh executable

Source setvars.sh using a new entrypoint script.

Source setvars.sh in a fail-safe way.

Disable cache mounts for builder apt commands.

Add apt lock timeouts to prevent builder and oneapi stages from
clashing.

Update .gitlab-ci.yml file to make builds sequential and prevent apt
locks.

Create a new debian image based on stable branch (Bullseye for now).
Use Intel Toolkits with Ubuntu 20.04 LTS (which are based on Debian 11).
This should prevent any GLIBC mismatch errors and other issues.

Update intel/oneapi-hpckit OS to Ubuntu 20.04 to prevent outdated
GLIBC errors.

Use Debian_base as the base image instead of oneAPI.
Final Lean image is based on oneAPI with required files copied from
staging.

spack still concretizies spack.yaml with oneapi compiler instead
of gcc. This test builds with --no-cache option to rule out spack.yaml
caching.
dev.Dockerfile has a CACHE_BUST arg for this purpose but it seems to be
set after copying spack.yaml not before. So if this works, move
CACHE_BUST before COPY instruction copying spack.

Previous build fails because spack concretizes environment to use
oneapi-2022.0.0 compiler instead of gcc mentioned in spack.yaml
This test modifies spack.yaml to use intel compiler instead to check
if dependencies compile successfully.

python-is-python3 is unavaliable for Ubuntu 18.04 apparently.
apt-get update before apt-get install should take care of this, but
is removed for the time being.

Previous testing failed due to intel/oneapi-hpckit not being used
despite being the first command in the Dockerfile.
The most probable cause is the name of the Dockerfile being the same as
jug/dev.Dockerfile.

Another change is the addition of another Build stage to reduce
final image size.

Modified GitLab CI Config for a minimal test run