Update file-based Import to be restartable

What does this MR do and why?

File-based Group/Project import can be interrupted due to auto-scaling or deployments. In this case, job is put back to the queue and picked back up. This results in the import failing and has to be restarted from scratch.

This MR makes it so the import skips already processed things and only imports the remaining information in the event of interruption and job restart. It tracks processed information in redis and skips records that were already processed.

⚠️ !181784 (merged) needs to be merged before this MR can be merged.

Mentions #382391 (closed)

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