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

Vert.x 4 includes a brand new support for OpenAPI, while this project supports only Vert.x 3

Describe the solution you'd like

Migrate the existing vertx web codegen to vert.x 4

Additional context

Should this live under a new codegen copy pasted from the previous one and migrated? Or should I just migrate the existing one?