[REQ] Add support for Helidon SE 4 client and server generation

[tjquinno]

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

This is for an enhancement not a bug fix.

Describe the solution you'd like

Helidon has released version 4.x. The Helidon-specific generators should support it.

Helidon has two "flavors"--SE (which does not rely on CDI or injection or MicroProfile) and MP (which does).

This issue captures the need to support Helidon SE 4.x (in addition to the existing support for earlier releases). (The separate issue #18261 addressed MP support.) The Helidon SE APIs changed significantly from 3.x to 4.x and the code generated from OpenAPI documents needs to reflect those changes.

The Helidon-specific generators for client and server--specifically, the SE libraries within each--need to be updated.

Describe alternatives you've considered

None available.

Additional context

n/a