Activitylog: Enable fallback for foldernames

[kobergj]

When listing the activity of a file shared-with-me, the activitylog would show User A uploaded file to {folder}. This is coming from the go templating system we use. We have a similar fallback for user names in the same service.

Acceptance Criteria

• If the {folder} cannot be fetched, use "shared-with-me" as fallback.
• This string needs to be translated