[REQ] Add support for Helidon 4.x MP

[tjquinno]

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 MP 4.x (in addition to the existing support for earlier releases).

Describe the solution you'd like

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

Describe alternatives you've considered

None available.

Additional Information

Helidon 4 MP implements the MicroProfile specs which have evolved but not radically since the Helidon 3.x timeframe. The incremental changes to support Helidon 4 MP are more limited than those for Helidon SE (which has quite significantly changed the APIs as compared to Helidon SE 3.x).

As a result, it seemed wise to update the MP library within the Helidon server and client generators separately from the SE library.