Pydiverse-pipedag

- Implement support for loading polars dataframes from DuckDB.
- Accelerate storing of dataframes (pandas and polars) to DuckDB (10-100x speedup).
- Fix `TypeError` being raised when using pydiverse transform SQLTableImpl together with a local table cache.

- Implemented automatic versioning of tasks by setting task version to [](AUTO_VERSION).
This feature is currently only supported by Polars [`LazyFrame`](inv:plreference/lazyframe/index) and by Pandas.
- Added [](kroki_url) config option.

- Allow invocation of undecorated task functions when calling task object outside of flow definition context.
- Rename `ignore_fresh_input` to `ignore_cache_function`.
- Fix race condition leading to `JSONDecodeError` in [](ParquetTableCache) when setting `store_input: true` together with the `DaskEngine`.
- Fix running subset of tasks not working due to tables and blobs being retrieved from wrong schema.

- Fix crash during config initialization when using [](DatabaseLockManager) together with `PostgreSQL`.

- Switch back to using numpy nullable dtypes for Pandas as default.
- Ensure that indices get created in same schema as corresponding table (IBM Db2).
- Fix private method `SQLTableStore.get_stage_hash`.

- Create initial documentation for pipedag.
- Remove stage argument from [](RawSql) initializer.
- Add [](RawSql) to public API.
- Fix [](PrefectTwoEngine) failing on retrieval of results.
- Added [](Flow.get_stage()), and [](Stage.get_task()) methods.
- Added [](MaterializingTask.get_output_from_store()) method to allow retrieval of task output without running the Flow.
- Created [TableReference](ExternalTableReference) to simplify complex table loading operations.
- Allow for easy retrieval of tables generated by [](RawSql).
Passing a RawSql object into a task results in all tables that were generated by the RawSql to be dematerialized.
The tables can then be accessed using `raw_sql["table_name"]`.
Alternatively, the same syntax can also be used during flow definition to only pass in a specific table.
- Fix private method `SQLTableStore.get_stage_hash` not working for IBM DB2.