[0 config] add new cli option to suppress the `MIXED_EXPORT` warning

[JounQin]

Clear and concise description of the problem

[MIXED_EXPORT] Warning: Entry module "index" is using named (including "cjsRequire", "configs", "createNodeResolver", "default", "flatConfigs", "importX", "importXResolverCompat", "meta", "rules") and default exports together. Consumers of your bundle will have to use `src/index.ts.default` to access the default export, which may not be what you want. Use `output.exports: "named"` to disable this warning.

Suggested solution

--output-exports named

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.