Aac-metrics

Added
- Parameters `timeout` and `separate_cache_dir` in `SPICE` function and class.
- Documentation pages with sphinx.
- Parameter `language` in `METEOR` function and class.
- Options to download only `PTBTokenizer`, `METEOR`, `SPICE` or `FENSE` in `download.py`.
- `SBERT` and `FluencyError` metrics extracted from `FENSE`.
- `SPIDErErr` metric which combines `SPIDEr` with `FluencyError`.
- Parameter `reset_state` in `SBERT`, `FluencyError`, `SPIDErErr` and `FENSE` functions and classes.

Changed
- Fix README typo and SPIDEr-max tables.

Fixed
- Workflow badge with Github changes. (https://github.com/badges/shields/issues/8671)

Added
- `FENSE` class and function metric, with fluency error rate and raw output probabilities.
- Unittest with `fense` repository.
- `load_metric` function in init to match huggingface evaluation package.

Changed
- Rename `global_scores` to `corpus_scores` and `local_scores` to `sents_scores`.
- Rename `CustomEvaluate` to `Evaluate` and `custom_evaluate` to `evaluate`.
- Set default cache path to `$HOME/.cache`.
- Remove 'coco' prefix to file, functions and classes names to have cleaner names.

Fixed
- `FENSE` metric error when computing scores with less than `batch_size` sentences.

Added
- All candidates scores option `return_all_cands_scores` for SPIDEr-max.
- Functions `is_mono_sents` and `is_mult_sents` to detect `list[str]` sentences and `list[list[str]]` multiples sentences.
- Functions `flat_list` and `unflat_list` to flat multiples sentences to sentences.

Changed
- Update default value used for `return_all_scores` in cider and rouge functions.
- Update internal metric factory with functions instead of classes to avoid cyclic dependency.

Fixed
- Fix SPIDEr-max local scores output shape.

Added
- Documentation for metric functions and classes.
- A second larger example for unit testing.

Changed
- Update README information, references and description.

Fixed
- SPIDEr-max computation with correct global and local outputs.
- Unit testing for computing SPICE metric from caption-evaluation-tools.

Added
- BLEU, METEOR, ROUGE-l, SPICE, CIDEr and SPIDEr metrics functions and modules.
- SPIDEr-max experimental implementation.
- Installation script in download.py.
- Evaluation script in evaluate.py.
- Unittest with `caption-evaluation-tools` repository.