feat(py): Base Python validator on schema instead of hard-coded regexes

[effigies]

trafficstars

With this PR, we can decouple the Python "validator" from the legacy validator, depending only on the schema.

Depends on bids-standard/bids-specification#1672 and #1957.

Closes https://github.com/bids-standard/bids-validator/issues/1821.

[codecov[bot]]

Codecov Report

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

Project coverage is 85.68%. Comparing base (fffc35c) to head (f103ac2).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1967   +/-   ##
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  Coverage   85.68%   85.68%           
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  Files          91       91           
  Lines        3792     3792           
  Branches     1220     1220           
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  Hits         3249     3249           
  Misses        457      457           
  Partials       86       86           

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[effigies]

@tsalo @Remi-Gau @sappelhoff If I could get a review from one of you on the Python, that would be greatly appreciated.