Add control code preview generation

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/control_codes/tasks.py

@@ -11,6 +11,17 @@ from .classes import ControlCode
 logger = logging.getLogger(__name__)
 
 
+@app.task()
+def task_generate_control_sheet_code_image(control_sheet_code_id):
+    ControlSheetCode = apps.get_model(
+        app_label='control_codes', model_name='ControlSheetCode'
+    )
+
+    control_sheet_code = ControlSheetCode.objects.get(pk=control_sheet_code_id)
+
+    return control_sheet_code.generate_image()
+
+
 @app.task(ignore_result=True)
 def task_process_document_version(document_version_id):
     DocumentVersion = apps.get_model(