Fix tuple equality with null values

[cmoesel]

Previously, if tuples had the same fields, and at least one field had a null value on one tuple and a non-null value on the other, then:

• if the null/non-null field came after a field with different values, it returned false (which is correct)
• if the null/non-null field came before a field with different values, it returned null (which is incorrect)

Now it will return the correct answer regardless of where the null/non-null field is.

NOTE: This PR does not fix npm audit issues or the codecov issue, as those have already been fixed in #326. As a result, this should be merged after #326.

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)
• All dependent libraries are appropriately updated or have a corresponding PR related to this change - N/A
• cql4browsers.js built with npm run build:browserify if source changed.

Reviewer:

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• 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