Default span attributes on data loading

[percevalw]

Changelog

Changed

• Deprecate the converters' (especially for BRAT/Standoff data) bool_attributes parameter in favor of general default_attributes. This new mapping describes how to set attributes on spans for which no attribute value was found in the input format. This is especially useful for negation, or frequent attributes values (e.g. "negated" is often False, "temporal" is often "present"), that annotators may not want to annotate every time.

Fixed

• Various improvements to the data processing related documentation pages

Checklist

• [x] If this PR is a bug fix, the bug is documented in the test suite.
• [x] Changes were documented in the changelog (pending section).
• [x] If necessary, changes were made to the documentation (eg new pipeline).

[codecov[bot]]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (9d2b58f) 96.87% compared to head (77db117) 96.93%.

Files	Patch %	Lines
edsnlp/processing/multiprocessing.py	97.71%	4 Missing :warning:
edsnlp/core/torch_component.py	98.03%	1 Missing :warning:
edsnlp/processing/simple.py	96.96%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #258 +/- ## ========================================== + Coverage 96.87% 96.93% +0.06% ========================================== Files 255 255 Lines 8438 8582 +144 ========================================== + Hits 8174 8319 +145 + Misses 264 263 -1 ```

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