✨(visio) use compatible with summary v2

This commit introduces the compatibility with summary v2.
It tecnically doesn't break the compatibility with v1 as
v1 params are still sent. But we advise people using the
transcribe feature in their own deployments to adapt to the
new v2 API, as this compatibility will be removed in a
future major version.

* RecordingStatusChoices now has
EXTERNAL_PROCESS_SUCCESSFUL
& EXTERNAL_PROCESS_FAILED
Values, which are changed by a new webhook that
can be called by the transcribe service.
This webhook is protected by its own bearer token.
* Title for the document is computed in visio,
* Tests are added / updated accordingly

src/backend/core/utils.py

@@ -459,12 +459,14 @@ def generate_upload_policy(file):
     return policy
 
 
-def generate_download_file_url(file, *, expires_in: int, override_domain: bool = True):
+def generate_download_s3_url(
+    key: str, *, expires_in: int, override_domain: bool = True
+):
     """
-    Generate a S3 signed download url for a given file.
+    Generate a S3 signed download url for a given key.
     """
-
-    key = file.file_key
+    if not key:
+        raise ValueError("key cannot be empty")
 
     # This setting should be used if the backend application and the frontend application
     # can't connect to the object storage with the same domain. This is the case in the