Update Spec Tests and Fix Newly Found Issues

[cmoesel]

This PR updates the spec-tests to mirror the latest tests in cqframework/cql-tests and fixes some of the issues that these tests reported. This brings us in closer alignment with other engines, surfaces possible areas of disagreement (see skip-list.txt), and highlights unimplemented features (also see skip-list.txt). Changes include:

• Add a README.md to test/spec-tests.
• Copy over all test cases and the test schema from cqframework/cql-tests.
• Update the test builder to handle the new <library> tag gracefully. It currently skips the one test that has a <library> tag since we haven't implemented that yet.
• Update skip-list.txt to remove skips that are now passing, add new skips as needed, and re-categorize other skips as appropriate.
• Update AllTrue logic to return true if the items list is null.
  • E.g., AllTrue(null) is now true.
• Update AnyTrue logic to return false if the items list is null.
  • E.g., AnyTrue(null) is now false.
• Update In and Contains overloads to treat null items as equal.
  • E.g., null in {null} and {null} contains null are now true.
• Update Includes and IncludedIn point/list overloads to treat null items as equal.
  • E.g., {null} includes null and null included in {null} are now true.
• Update Includes and IncludedIn list/list overloads to treat null items inside of lists as equal.
  • E.g., {null} includes {null} and {null} included in {null} are now true.
• Update Includes and IncludedIn list/list overloads to return null if either list argument is null.
  • E.g., null as List<String> includes {'a'}, {'a'} includes null as List<String>, null as List<String> included in {'a'}, {'a'} included in null as List<String> are now all null.
• Update ReplaceMatches to support escaping $ in the substitution by using \$.
  • E.g., ReplaceMatches('All that glitters is not gold', '\\s', '\\$') is 'All$that$glitters$is$not$gold'.
• Update aggregation queries to not be distinct by default.
  • E.g., ({1, 2, 3, 3, 4}) L aggregate A starting 1: A * L is 72 (not 24).

To test:

• Run npm run build:all and verify there are no changes
• Run npm test and verify tests pass

Fixes #318

Submitter:

• This pull request describes why these changes were made
• Code diff has been done and been reviewed (it does not contain: additional white space, not applicable code changes, debug statements, etc.)
• Tests are included and test edge cases
• Tests have been run locally and pass
• Code coverage has not gone down and all code touched or added is covered.
• Code passes lint and prettier (hint: use npm run test:plus to run tests, lint, and prettier)
• [N/A] All dependent libraries are appropriately updated or have a corresponding PR related to this change
• cql4browsers.js built with npm run build:browserify if source changed.

Reviewer:

Name: @hossenlopp

• Code is maintainable and reusable, reuses existing code and infrastructure where appropriate, and accomplishes the task’s purpose
• The tests appropriately test the new code, including edge cases
• You have tried to break the code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.47%. Comparing base (88c80e7) to head (31ff87d).
⚠️ Report is 9 commits behind head on master.

Files with missing lines	Patch %	Lines
src/elm/list.ts	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #348      +/-   ##
==========================================
+ Coverage   87.40%   87.47%   +0.06%     
==========================================
  Files          52       52              
  Lines        4558     4566       +8     
  Branches     1288     1291       +3     
==========================================
+ Hits         3984     3994      +10     
+ Misses        361      358       -3     
- Partials      213      214       +1     

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[elsaperelli]

Just a few comments to get input from @hossenlopp on, otherwise looks great!