support apiPrefix parameter

[ender74]

I have to different swagger files with same basePath (like /api). I would like to generate spring-boot server stups out of it. This results in two identical named classes (e.g. "ApiApiController") which then results in colliding bean names:

Caused by: org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'apiApiController' for bean class [de.zalando.ale.asgateway.api.sorter.ApiApiController] conflicts with existing, non-compatible bean definition of same name and class [de.zalando.ale.asgateway.api.wms.ApiApiController]

To prevent this, i would like to be able to configure a Prefix which will be added to the generated Api Classnames.