[nodejs-express-server] Remove the new Promise antipattern

Description

Hello,

there is a useless instanciation of a new Promise in the service template:
https://github.com/OpenAPITools/openapi-generator/blob/a58441cf68171456c3a76c9f2b1745b21a3eae69/modules/openapi-generator/src/main/resources/nodejs-express-server/service.mustache#L24

Because of its presence in generated code, it spreads some bad practices regarding the usage of promises in Javascript: In this case we would simply need to return from the service, either a simple object or a promise instanciated by a call to a DB..., in wery limited occasion we would need to return a new Promise by ourselves.

Proposed resolution

const {{{operationId}}} = ({{#allParams}}{{#-first}}{ {{/-first}}{{paramName}}{{#hasMore}}, {{/hasMore}}{{#-last}} }{{/-last}}{{/allParams}}) => {
  try {
    return Service.successResponse({
  {{#allParams}}
    {{paramName}},
  {{/allParams}}
    }));
  } catch (e) {
    throw Service.rejectResponse(
    e.message || 'Invalid input',
    e.status || 405,
    ));
  }
};

Additional context, some references

https://hackernoon.com/javascript-promises-best-practices-anti-patterns-b32309f65551

https://runnable.com/blog/common-promise-anti-patterns-and-how-to-avoid-them
see "Creating new Promises"

Start with modules/openapi-generator/src/main/resources/nodejs-express-server/service.mustache at the referenced operation template and inspect the generated Node.js Express service output. Remove the unnecessary Promise wrapper while preserving the shown response and error handling, then verify the generated service behavior with the relevant generator tests if available.