[SCHEMA] Check sidecar fields mentioned in rule checks exist in the schema

[Remi-Gau]

• closes none but relates to [FIX] typo #1910 (comment)

[Remi-Gau]

I sort of totally improvised testing this, so there may be a simpler way to do this.

[Remi-Gau]

FYI this actually caught a few typos or things that had not been updated in the schema.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.23%. Comparing base (7f1f673) to head (ed1c597).
Report is 113 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1917   +/-   ##
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  Coverage   87.23%   87.23%           
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  Files          16       16           
  Lines        1410     1410           
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  Hits         1230     1230           
  Misses        180      180           

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[effigies]

Largely rewrote to fetch any identifier, whether it's a bare (suffix), a function name (exists) or a property (nifti_header.dims). This way we can add more checks easily at the top level.

I'm not going to bog this PR down with other checks, but, for example, we could make sure that nifti_header fields exist in schema.meta.context.properties.nifti_header.properties, or schema.* can be found in the schema itself.

I didn't find any new typos from what you already found by expanding to all rules that include selectors.

[Remi-Gau]

Thanks for the review and expansion.
At least this provides a framework to expand on.