Support Permitted Users for S3 Settings via Config User Key

Why it matters

This feature allows finer access control by restricting specific S3 configurations to a whitelist of users, enhancing security and ensuring that only authorized users can use particular S3 settings.

How to use it

In the ClickHouse configuration file, under the S3 settings section, add the user key with a list of permitted usernames to restrict access. For example:

s3:
  custom_settings:
    user: ["user1", "user2"]
    ...

This restricts the S3 setting to the users specified in the list.