Enh/bep036 extensions

[rwblair]

Add zip and glob to expression language.
Add dirEntities to file context.
Add root level session.tsv to dataset context.

Not all these may end up being needed depending on how the final rules shake out.

[codecov]

Codecov Report

❌ Patch coverage is 73.54839% with 41 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.04%. Comparing base (6eaae4e) to head (e0188f9).

Files with missing lines	Patch %	Lines
src/utils/deepEquals.ts	15.38%	19 Missing and 3 partials ⚠️
src/schema/tables.ts	37.50%	9 Missing and 1 partial ⚠️
src/schema/expressionLanguage.ts	93.25%	4 Missing and 2 partials ⚠️
src/validators/bids.ts	40.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #366      +/-   ##
==========================================
- Coverage   87.35%   87.04%   -0.31%     
==========================================
  Files          65       66       +1     
  Lines        4799     4947     +148     
  Branches      782      816      +34     
==========================================
+ Hits         4192     4306     +114     
- Misses        513      542      +29     
- Partials       94       99       +5     

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[rwblair]

_walk call added to expressionlanguage.ts should be memoized separately.

Original glob implementation had split the pattern to match by / and would abandon testing branches of the file tree that failed as it walked. I couldn't figure out a clean way to make this work with ** so I went for the knuckle dragging but compact seen here.