[k6] Swagger code generator for k6 API load-testing tool (ES5.1+)

[mostafa]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
• Filed the PR against the correct branch: 3.0.0 branch for changes related to OpenAPI spec 3.0. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

Description of the PR

k6 is an API load-testing tool created by Load Impact AB to help developers and DevOps people test the performance of their APIs. It is written in Go, and is scriptable in JavaScript, supporting ES5.1+. At Load Impact, we have converters/codegens for HAR files, Postman collections and JMeter to help users of k6 easily be onboard to our tool.

Since we focus on API load-testing, we thought it would be a good idea to create a Swagger/OpenAPI code generator, too. So, after much research, we found that this project is the officially developed and maintained one that we can reliably put our efforts on. Thus we created this code generator, to help generate k6 scripts from Swagger 2.0 specification documents.

This is our first PoC and we definitely would like to hear your feedback to improve it further. There are some questions for the official maintainers:

1. Should we also edit the README.md and add ourselves as Template Creators and Technical Committee for k6?
2. Does our implementation seem like a good starting point for further improving the project?

We really appreciate your feedback on this.