[REQ] Hide @ApiIgnore when using useSpringfox=false

Is your feature request related to a problem? Please describe.

I'm using spring generator with springfox disabled (useSpringfox=false).
However, the generated API still contains springfox ApiIgnore import reference. In my setup this is an unused import, since it is only required when you have vendorExtensions.x-spring-paginated or reactive enabled.

Describe the solution you'd like

I think we can duplicate this import inside both reactive and vendorExtensions.x-spring.paginated sections. This way it will not be present by default and will be defined if either of flags is enabled. It will be defined twice if both flags are true, but it doesn't look like an issue to me.

Describe alternatives you've considered

We can also simply hide the import itself with useSpringfox=false, but this will make an implicit dependency on this flag when we enable reactive or vendorExtensions.x-spring-paginated.

Additional context

I can make a PR if the solution is ok or would be glad to hear other options.

Start in modules/openapi-generator/src/main/resources/JavaSpring/api.mustache, reviewing the ApiIgnore import and the reactive and vendorExtensions.x-spring-paginated sections. Check generated JavaSpring APIs with useSpringfox=false and confirm the import is absent by default but present when either relevant option requires it.