[REQ] Generate one avro-schema file from OpenAPI's multiple components

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

I'm using kafkajs which requires to create avsc files explicitly, thanks to avro-schema implementation I can generate the avsc files from an OpenAPI file... but my OpenAPI contains hundreds of components (#/components/schemas/XXX), as a consequence openapi-generator generates hundreds of avsc files...

Describe the solution you'd like

Today I use this command:

$OPENAPI_GENERATOR generate -i $SOURCE_PATH -g $DESTINATION_FORMAT -o $DESTINATION_PATH --additional-properties packageName=$PACKAGE_NAME

=> This generates as much avsc files as OpenAPI components in the OpenAPI file, but I only need a single MyRootComponent.avsc from my OpenAPI (#/components/schemas/MyRootComponent)

I would like to say which is my root OpenAPI component with a rootComponent parameter:

$OPENAPI_GENERATOR generate -i $SOURCE_PATH -g $DESTINATION_FORMAT -o $DESTINATION_PATH --additional-properties packageName=$PACKAGE_NAME rootComponent=MyRootComponent

=> This would generate a single MyRootComponent.avsc file that embbeds all the required OpenAPI components directly inside the MyRootComponent record

Start with the linked avro-schema generator documentation and reproduce the shown command against an OpenAPI document containing multiple components. The change is complete when a rootComponent option such as MyRootComponent produces one MyRootComponent.avsc containing all required components instead of one file per component.