[NodeJS/Javascript ] Opeanpi examples support + better JSDOC

[ymoran00]

When using the too create nodejs-express-server code, the openapi examples weren't supported.
This meant that it was impossible to have mocks on the automatically generated server.
Added examples support here, implementation copied from mustache in swagger-codegen-cli repo.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• File the PR against the correct branch: master (5.3.0), 6.0.x
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[wing328]

@ymoran00 thanks for the PR.

cc @YishTish

[wing328]

CI failure not related to this change.

[wing328]

@ymoran00 thanks for the PR. Can you please PM me via Slack when you've time to discuss this PR?

https://join.slack.com/t/openapi-generator/shared_invite/enQtNzAyNDMyOTU0OTE1LTY5ZDBiNDI5NzI5ZjQ1Y2E5OWVjMjZkYzY1ZGM2MWQ4YWFjMzcyNDY5MGI4NjQxNDBiMTlmZTc5NjY2ZTQ5MGM

[amitpareek2]

Hi @ymoran00 , @wing328 , Im also looking for this feature . Can I ask you if there is a timeline for this or it is implemented in latest release ?

[wing328]

@ymoran00 Should we keep async here?