Feature : Support building prepared container on top of non already pulled OCI image

Current error :

```bash
[LUMI-SD][Container preparation] Entering entrypoint
[LUMI-SD][Container preparation] Encryption mode is on. Registering and running SPIRE Agent
[LUMI-SD][Container preparation] Run container preparation
Checking the access to docker socket at /var/run/docker.sock
Building SD-CONTAINER ready OSI image
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/docker/api/client.py", line 265, in _raise_for_status
response.raise_for_status()
File "/usr/local/lib/python3.9/site-packages/requests/models.py", line 1021, in raise_for_status
raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: http+docker://localhost/v1.44/images/talinx/jp2a/json

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/container_preparation/./prepare_container.py", line 28, in
prepared_image_tag = build_prepared_image(
File "/container_preparation/lib/image_build.py", line 78, in build_prepared_image
dockerfile_obj = generate_prepared_dockerfile(
File "/container_preparation/lib/image_build.py", line 24, in generate_prepared_dockerfile
base_image = docker_client.images.get(base_image_tag)
File "/usr/local/lib/python3.9/site-packages/docker/models/images.py", line 333, in get
return self.prepare_model(self.client.api.inspect_image(name))
File "/usr/local/lib/python3.9/site-packages/docker/utils/decorators.py", line 19, in wrapped
return f(self, resource_id, *args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/docker/api/image.py", line 251, in inspect_image
return self._result(
File "/usr/local/lib/python3.9/site-packages/docker/api/client.py", line 271, in _result
self._raise_for_status(response)
File "/usr/local/lib/python3.9/site-packages/docker/api/client.py", line 267, in _raise_for_status
raise create_api_error_from_http_exception(e) from e
File "/usr/local/lib/python3.9/site-packages/docker/errors.py", line 39, in create_api_error_from_http_exception
raise cls(e, response=response, explanation=explanation) from e
docker.errors.ImageNotFound: 404 Client Error for http+docker://localhost/v1.44/images/talinx/jp2a/json: Not Found ("No such image: talinx/jp2a:latest")
Cleaning everything before leaving ...
```

This error comes from the fact that the user didn't run

```bash
docker pull talinx/jp2a
```
beforehand.

We could modify this code's behaviour to pull image if it doesn't exist