Databento integration

[cjdsellers]

Add an initial integration for Databento covering US equities, futures, options on futures and equity options.

• Data loader for Databento Binary Encoding (DBN) files
• Feeding backtest engines with decoded DBN -> Nautilus data
• Writing from decoded DBN -> Nautilus Parquet format with the data catalog
• Rust client library integration for historical requests & live data feeds

Still to go:

• Write Databento integration guide
• Improve the code and efficiency a little more (can always improve this)
• Re-add support for MBP-10 (L2 order book data, top 10 levels aggregated snapshots)
• Add support for imbalance and statistics schemas
• Add support for continuous, parent and instrument_id symbology types
• Test with more backtest and live examples
• Add some more test coverage generally
• Write how to setup a Databento data catalog guide
• Write some per asset class examples

[wayneadams]

Up voting for priority planning 🙏