GitLab Migration - import relations compressed with zip

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As discussed in POC #376261 (closed) GitLab Migration should start supporting relations import compressed with zip.

Proposed solution

1. Update BulkImports::FileDownloadService to be able to download relation.zip along side with relation.tar.gz
2. Update BulkImports::FileDecompressionService to be able to decompress .zip files along side with .tar.gz depending on type of the compression used (by updating the class itself or using composition/inheritence to achieve this)
3. Since in case of .zip there is no Tar involved, we should update the codebase to not do any systemcalls to tar when decompressing data with zip
4. Make sure all pipelines import data same as before
5. Put changes behind a short lived feature flag. Since we're going to be supporting both types of files for some time it makes sense to have the feature flag for testing purposes until we iron out any found issues