This PR implements a test server that exposes a $cql target to allow the CQL Tests Runner to run tests against the cql-execution engine. Rather than repeat all the details here, I'll refer you to the test-server/README.md file in this branch.

I initially developed this as a standalone project outside of cql-execution that pulled in cql-execution as an NPM dependency. This PR integrates it into the cql-execution project as a sub-project with its own package.json and configuration files. In addition to general review of the code, I'm also interested in thoughts on this approach. Should we:

• Keep it as I have it here (a sub-project)?
• Keep it in cql-execution but try to integrate it more closely (i.e., share package.json and configuration files)?
• Or introduce it as a completely separate project outside of cql-execution (and if so, where)?

I have not yet invested in updating GitHub actions to automatically run the tests or other checks in the sub-project. I will do that after we have confirmed the approach.

NOTE: The npm audit check is currently failing due to a reported vulnerability in elliptic. There is currently no fix for that.

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:

Name:

• 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