Heartbeat backfill

[michaeldjeffrey]

Backfill CLI command for heartbeats

• heartbeat timestamp is the received_timestamp from ingest
• we don't have historical asserted locations

Many of the early heartbeat files contain ~500k valid heartbeats.

Locally, I've been running with a --batch-size 20,000,000 as to not create a snapshot per file.
This gives us an arrow file of ~2.5Gb before upload. The parquet files in iceberg are ~32Mb.

Because of the size of heartbeat files, and the constraints we've been running the backfill jobs with, I would suggest also providing --batch-timeout 30min so we don't roll the default 1min and create a load of snapshots while waiting on parsing.

(--batch-size and --batch-timeout were also added as args for bans, speedtests, and speedtest-avgs.)