[Java] implicit headers regex

Fix for: https://github.com/OpenAPITools/openapi-generator/issues/8166 & https://github.com/OpenAPITools/openapi-generator/issues/11540

Add new config option implicitHeadersRegex that can be configured via additionalProperties. This property can be used to specify regex for all headers that should not be added to generated server/client code. This new feature is backward compatible with old one implicitHeaders which was used for Spring & Java-PKMST generators. Once implicitHeaders=true the implicitHeadersRegex is ignored

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