Support for a filesystem param in all edsnlp.data readers/writers

[percevalw]

Description

• Support for a filesystem parameter in every edsnlp.data.read_* and edsnlp.data.write_* functions

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

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.12%. Comparing base (226951d) to head (bbb743b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #274 +/- ## ========================================== + Coverage 97.07% 97.12% +0.05% ========================================== Files 256 257 +1 Lines 8677 8703 +26 ========================================== + Hits 8423 8453 +30 + Misses 254 250 -4 ```

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