[kotlin-server][JAX-RS] Fix class names for useTags

[feczkob]

Follow-up of #23379.
Fixes #23414

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---

Summary by cubic

Fixes JAX-RS kotlin-server class naming and @Path generation when useTags is false or omitted, and consistently applies class-level common paths across JAX-RS. Operations are grouped by the first path segment with a class-level base path and trimmed method paths.

• Bug Fixes
  • JAX-RS (jaxrs-spec): when useTags=false or missing, group operations by base path; fall back to default if the base path is empty or templated.
  • Compute commonPath for all JAX-RS classes; set class-level @Path to it (empty for root) and emit method @Path only for sub-resources.
  • Update templates: docs now use {{commonPath}}{{path}}; JAX-RS interface renders method @Path only when needed.
  • Update tests, configs, and regenerated samples to reflect correct class names and paths.

^{Written for commit 7a365ce. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 14 files

[feczkob]

I used this repo for reproduction, thanks to @lbilger: https://github.com/lbilger/openapi-generator-path-shadowing-reproducer

JAXRS-SPEC, useTags = true

kotlin-server, JAXRS-SPEC, useTags = true

JAXRS-SPEC, useTags = false

kotlin-server, JAXRS-SPEC, useTags = false

JAXRS-SPEC, no useTags

kotlin-server, JAXRS-SPEC, no useTags