fix(import): don't re-import archived manuscripts from semantic scholar

See #1594 (closed). We had a regression caused by my misunderstanding requirements and changing code so that Semantic Scholar would re-import a manuscript if it had been archived. But we should not reimport archived manuscripts.

In the process of testing this I had a lot of trouble with CoLab bioRxiv imports: queries to the bioRxiv server were slow and frequently failing. I ended up implementing timeout and retries to make these queries more robust.