Re-implement local queue on Zeno v2 using sqlite

[yzqzss]

Notes:

• Uses a cgo-free SQLite client: https://github.com/ncruces/go-sqlite3
• sqlc_model package is generated by sqlc
• To ensure that seeds with the same URL.Value are only queued once (deduplication), I revertd the local seencheck part of 2a6535d to perform seencheck on top level seeds. (cc: @equals215)

Future Work:

• We need a "globalStopper" that calls controler.Stop() when everything is finished.
• Most of local queue code is Ctrl-CV from the hq package, maybe it/they could be simplified a bit.
• The batchsize and workersize could to be fine-tuned for sqlite.