Sockeye

Fixed
- Do not mask prepended tokens by default (for self-attention).
- Do not require specifying `--end-of-prepending-tag` if it is already done when preparing the data.

Fixed
- Two small fixes to SampleK. Before the device was not set correctly leading to issues when running sampling on GPUs. Furthermore, SampleK did not return the top-k values correctly.

Added

- Sockeye now supports blocking cross-attention between decoder and encoded prepended tokens.
- If the source contains prepended text and a tag indicating the end of prepended text,
Sockeye supports blocking the cross-attention between decoder and encoded prepended tokens (including the tag).
To enable this operation, specify `--end-of-prepending-tag` for training or data preparation,
and `--transformer-block-prepended-cross-attention` for training.

Changed

- Sockeye uses a new dictionary-based prepared data format that supports storing length of prepended source tokens
(version 7). The previous format (version 6) is still supported.

Fixed

- Fixed sequence copying integration tests to correctly specify that scoring/translation outputs should not be checked.
- Enabled `bfloat16` integration and system testing on all platforms.

Added

- Added support for `--dtype bfloat16` to `sockeye-translate`, `sockeye-score`, and `sockeye-quantize`.

Fixed

- Fixed compatibility issue with `numpy==1.24.0` by using `pickle` instead of `numpy` to save/load `ParallelSampleIter` data permutations.

Changed

- Running `sockeye-evaluate` no longer applies text tokenization for TER (same behavior as other metrics).
- Turned on type checking for all `sockeye` modules except `test_utils` and addressed resulting type issues.
- Refactored code in various modules without changing user-level behavior.