Merge core functionality into configuration.py

Which is the file `docker/configuration.docker.py` in our repo.
The common code is then imported by `docker/ldap_config.docker.py`.

docker/ldap_config.docker.py

@@ -1,12 +1,9 @@
-from os.path import abspath, isfile
-from os import scandir
-import importlib.util
-import sys
+from .configuration import read_configurations
 
-_CONFIG_DIR = '/etc/netbox/config/ldap/'
-_MAIN_CONFIG = 'ldap_config'
-_MODULE = 'netbox.configuration.ldap'
-_loaded_configurations = []
+_loaded_configurations = read_configurations(
+  config_dir = '/etc/netbox/config/ldap/',
+  config_module = 'netbox.configuration.ldap',
+  main_config = 'ldap_config')
 
 
 def __getattr__(name):
@@ -16,46 +13,3 @@ def __getattr__(name):
     except:
       pass
   raise AttributeError
-
-
-def _filename(f):
-  return f.name
-
-
-def _import(module_name, path):
-  spec = importlib.util.spec_from_file_location('', path)
-  module = importlib.util.module_from_spec(spec)
-  spec.loader.exec_module(module)
-  sys.modules[module_name] = module
-
-  _loaded_configurations.insert(0, module)
-
-  print(f"🧬 loaded config '{path}'")
-
-
-_main_config_path = abspath(f'{_CONFIG_DIR}/{_MAIN_CONFIG}.py')
-if isfile(_main_config_path):
-  _import(f'{_MODULE}.{_MAIN_CONFIG}', _main_config_path)
-else:
-  print(f"⚠️ Main configuration '{_main_config_path}' not found.")
-
-with scandir(_CONFIG_DIR) as it:
-  for f in sorted(it, key=_filename):
-    if not f.is_file():
-      continue
-
-    if f.name.startswith('__'):
-      continue
-
-    if not f.name.endswith('.py'):
-      continue
-
-    if f.name == f'{_MAIN_CONFIG}.py':
-      continue
-
-    module_name = f"{_MODULE}.{f.name[:-len('.py')]}".replace(".", "_")
-    _import(module_name, f.path)
-
-if len(_loaded_configurations) == 0:
-  print(f"‼️ No configuration files found in '{_CONFIG_DIR}'.")
-  raise ImportError(f"No configuration files found in '{_CONFIG_DIR}'.")