Backward compatibility to support CommonJS

[mastepanoski]

Description

Currently if I want to use this module in a project that has not implemented ESM support yet, I get the following error: Error [ERR_REQUIRE_ESM]: require() of ES Module ...someprj/node_modules/@keycloak/keycloak-admin-client/lib/index.js

So tsconfig.json and package.json could be modified to support ESM and CommonJS.

Discussion

No response

Motivation

It would be good to provide backward compatibility to commonjs projects until ESM is widely adopted.

Details

Implementation ideas: Using a hybrid approach https://www.sensedeep.com/blog/posts/2021/how-to-create-single-source-npm-module.html

[jonkoops]

Duplicate of #523