Basing extraction-worker on nodejs disallows usage in the browser

[TimDaub]

• for @wighawag's browser based conquest eth crawler, extraction-worker that implements proper pooling, potentially weiroll, queue prioritization and other features could be useful
• but at least for now, extraction-worker was specifically designed to be used in nodejs and so it may use node-specific packages
• a few problematic ones may include: eth-fun, debug, worker_threads, process, fastq
• it'd be nice if extraction-worker was available for use in the browser as a small package too

[TimDaub]

I looked through eth-fun and it only requires Buffer