Use passed in executionDateTime timeZoneOffset when available

[elsaperelli]

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Summary

Previously, getDateTime() in dateTime.ts was not passing in a timeZoneOffset when creating a new DateTime. We only want to do this if an executionDateTime is not provided since it will set the timeZoneOffset to the timeZoneOffset of the evaluation. In the case where the executionDateTime is passed in, we want the timeZoneOffset to come from that. We now achieve this by passing the ctx.getExecutionDateTime().timeZoneOffset to functions that call getDateTime().

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
• [✔] cql4browsers.js built with npm run build:browserify if source changed.

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• Code is maintainable and reusable, reuses existing code and infrastructure where appropriate, and accomplishes the task’s purpose
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[codecov-commenter]

Codecov Report

Merging #313 (ad16658) into master (5e1b210) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head ad16658 differs from pull request most recent head 877578c. Consider uploading reports for the commit 877578c to get more accurate results

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@@           Coverage Diff           @@
##           master     #313   +/-   ##
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  Coverage   86.15%   86.15%           
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  Files          52       52           
  Lines        4506     4508    +2     
  Branches     1270     1270           
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+ Hits         3882     3884    +2     
  Misses        324      324           
  Partials      300      300           

Files Changed	Coverage Δ
src/datatypes/datetime.ts	89.48% <100.00%> (ø)
src/elm/clinical.ts	82.64% <100.00%> (+0.14%)	⬆️
src/elm/type.ts	81.15% <100.00%> (+0.06%)	⬆️

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[cmoesel]

Thanks for this PR, @elsaperelli. It looks really good! I only made a couple of very minor comments -- none of which affect the actual code (just code comments and a test description).

[cmoesel]

This looks good! Thanks for making the engine better!