Implement the get_rdf_private_datasets_with_access_token feature

First really raw but working test version that implements the possibility to load private rdf datasets with access tokens from the GitLab RWTH instance. The code isn't commented out sufficiently and the procedure logic needs a clean rework since there are a lot of edge cases.

fst_rdf_utilities__python_package/fst_rdf_utilities_py/utilities.py

 import re
 from pathlib import Path
+import base64
 from copy import deepcopy
 import sys
 # sys.setrecursionlimit(5000)
@@ -279,6 +280,17 @@ def get_git_instance_service(url: str) -> str:
     return git_instance_name
 
 
+def get_GitLab_file_content_and_version_commit_id(url, access_token:str=None):
+    # TODO: declare this function as private and create a get_rdf_file_content_and_version_commit_id function and add
+    #  at position one a argument service_id or service_name and match it to the supported ones and call the private
+    #  functions.
+    if access_token:
+        headers = {'PRIVATE-TOKEN': access_token}
+    else:
+        headers = None
+    return_variables_dict = parse_url_into_parts(url)
+
+
 
     api_base_url = f"{return_variables_dict['base_url']}/api/v4/"
 
@@ -286,7 +298,10 @@ def get_git_instance_service(url: str) -> str:
     # Get project id
     with requests.Session() as s:
         project_path_url_encoded = requests.utils.quote(return_variables_dict['project_path_url'], safe='')
-        r = s.get(f"{api_base_url}/projects/{project_path_url_encoded}")
+        if headers:
+            r = s.get(f"{api_base_url}/projects/{project_path_url_encoded}", headers=headers)
+        else:
+            r = s.get(f"{api_base_url}/projects/{project_path_url_encoded}")
 
     projectid = r.json()['id']  # '84807'
 
@@ -295,11 +310,17 @@ def get_git_instance_service(url: str) -> str:
         URLencodedfilepath = requests.utils.quote(return_variables_dict['repository_file_path'], safe='')
         # TODO: FIXME: tokens from a token vault need to be used here
         # TODO: main branch is sleected, might be a problem in the future if useres aren't consistent with their branches
-        # headers = {'PRIVATE-TOKEN': 'glpat-rFxz7TPcPugTsPSneuLk'}
-        response = s.get(
-            f'{api_base_url}/projects/{projectid}/repository/files/{URLencodedfilepath}?ref=main')  # , headers=headers)
+        file_api_url = f'{api_base_url}/projects/{projectid}/repository/files/{URLencodedfilepath}?ref=main'
+        if headers:
+            response = s.get(file_api_url, headers=headers)
+        else:
+            response = s.get(file_api_url)
+
+    # Decode the Base64 encoded content of the file
+    decoded_content = base64.b64decode(response.json()['content']).decode('utf-8')
+    # TODO: Check if the encoding is base64 and what the https encoding (usually utf-8) is
 
-        return response.json()['commit_id']
+    return decoded_content, response.json()['commit_id']
 
 
 # def save_sensor_rdf_as_mat_file(pID_url: str, save_to_directory_path: [Path, str]) -> None: