Add a tool to dump SLS traces and batch ingest traces for analysis

[ekzhu]

To analyze traces offline, we should support a tool for dumping the production SLS traces given a time period, while ensuring the game boundaries are intact.

Also another script tool to batch ingest traces into a local trace store for analysis and backtesting (after #223).

[ekzhu]

We can maintain a public OSS bucket for historical dumps.

[cyruszhang]

oss backup infra is already supported. will utilize it