[Task] Make code generation more convenient

[atextor]

Is your task related to a problem? Please describe.
As demonstrated in the esmf-sdk-demo, setting up usage of the esmf-maven-plugin in conjunction with openapi-generator is tedious and error-prone. There should be way to do "all in one" code generation from the Maven plugin.

Describe the solution you'd like

• Introduce a Maven goal that is equivalent to chaining OpenAPI generation, (openapi-generator-based) code genereation and Java code generation
• Enable resolution configuration for resolvers such as the GitHub resolver (including reasonable token configuration)