[BUG] Metadata option is not supported in CLI, Maven and Gradle plugin

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue? (N/A)
• Have you validated the input using an OpenAPI validator (example)? (N/A)
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The generateMetadata option is not supported in CLI, Maven and Gradle plugin. Hence, there is no option to deactivate metadata output despite the flag exists.

openapi-generator version

master

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Try to set the generate metadata option, it is not available.

Related issues/PRs

#13699 adds this for Maven and Gradle plugin, but not for CLI. It does so via global properties.

Suggest a fix

Like #13699 and also add support to CLI. Re #13699 it can be discussed if this should be solved via global properties or not.

Start by tracing the generateMetadata and global-properties handling added in #13699, then compare the CLI, Maven, and Gradle plugin paths. Done means the option is consistently available across all three interfaces and can disable metadata output; verify each interface with its existing generation checks.