Fetching config in file artifact snapshot breaks offline mode #885

Description of Bug

Inside FileArtifact, if snapshot=True, the UserConfiguration is fetched. However since mode is not passed through, it does it in online mode, which breaks offline mode as it continually tries to ping the server

Maybe mode should be a required arg in fetch()?

Also we should have a CI job which runs offline mode tests fully offline, ie there is no server URL or token available

Steps To Reproduce

Steps to reproduce the behavior:

1. Create an offline mode run
2. Remove internet connection
3. Save a file artifact with snapshot = True

Expected behavior

File artifact should save locally with a copy of the file in cache

Actual Behaviour

Run breaks since it tries to obtain server version, as UserConfiguration thinks it is in online mode

Screenshots

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Setup

• OS: Ubuntu
• Python version: v3.10

Additional context

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