fix(kotlin-spring): container inline enums must not get override val value

EnumValueInterfaceUtils.injectInPostProcessModelsEnum() adds
ValuedEnum<...> to x-kotlin-implements only for `var.isEnum &&
!var.isContainer`, but dataClass.mustache emitted the `override` keyword
for every enum whenever useEnumValueInterface=true. Container inline
enums therefore produced uncompilable Kotlin (`overrides nothing`) since
the enum class did not actually implement any interface to override.

Gating the `override` token on `^isContainer` keeps the template in sync
with the util.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Picazsoo

modules/openapi-generator/src/main/resources/kotlin-spring/dataClass.mustache

@@ -48,7 +48,7 @@
     * {{{description}}}
     * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
     */
-    enum class {{{nameInPascalCase}}}(@get:JsonValue {{#useEnumValueInterface}}override {{/useEnumValueInterface}}val value: {{#isContainer}}{{#items}}{{{dataType}}}{{/items}}{{/isContainer}}{{^isContainer}}{{{dataType}}}{{/isContainer}}) {{#vendorExtensions.x-kotlin-implements}}{{#-first}}: {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}} {{/vendorExtensions.x-kotlin-implements}}{
+    enum class {{{nameInPascalCase}}}(@get:JsonValue {{#useEnumValueInterface}}{{^isContainer}}override {{/isContainer}}{{/useEnumValueInterface}}val value: {{#isContainer}}{{#items}}{{{dataType}}}{{/items}}{{/isContainer}}{{^isContainer}}{{{dataType}}}{{/isContainer}}) {{#vendorExtensions.x-kotlin-implements}}{{#-first}}: {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}} {{/vendorExtensions.x-kotlin-implements}}{
 {{#allowableValues}}{{#enumVars}}
         {{{name}}}({{{value}}}){{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}};