Integrate with django's custom file storage settings

[WhyNotHugo]

We currently use a few custom settings (e.g.: AFIP_KEY_STORAGE, AFIP_CERT_STORAGE) to define storages.

Django 4.2 implements a standard mechanism for defining custom storages. We should move over to use that.

See: https://docs.djangoproject.com/en/4.2/releases/4.2/#custom-file-storages

[spuigdengolas]

One example of custom storage backend could be the following. This setting makes files uploaded to S3 private.

storages.py

from django.core.files.storage import get_storage_class
from storages.backends.s3boto3 import S3Boto3Storage

class PrivateMediaStorage(S3Boto3Storage):
    location = "media/private"
    default_acl = "private"
    file_overwrite = False
    custom_domain = False

    def __init__(self):
        super().__init__()
        self.bucket_name = settings.AWS_PRIVATE_STORAGE_BUCKET_NAME

def select_private_storage():
    # important
    private_storage_class = get_storage_class(settings.PRIVATE_FILE_STORAGE)
    return private_storage_class()  # instantiate the storage

production.py

PRIVATE_FILE_STORAGE = "my_project.utils.storages.PrivateMediaStorage"

AFIP_PDF_STORAGE = PRIVATE_FILE_STORAGE