Support DescribeCluster v0 API

Who is this for and what problem do they have today?

The DescribeCluster API is currently not supported by Redpanda. It returns the cluster_authorized_operations which can be used by administrator tools such as Console to reflect the available permissions of the used Kafka user in the frontend. This way we can for example render a Create ACL button as disabled if the user does not posses the permission to do so.

What are the success criteria?

Why is solving this problem impactful?

• DescribeCluster v0 is supported and fully compliant with the reference configuration
• Better Kafka API compatibility

Additional notes

• KIP-700 describes this new API
• The same property is exposed via metadata v8 (requested via https://github.com/redpanda-data/redpanda/issues/18670), but it has been removed there with metadata v11 in favour of exposing it via the DescribeCluster API. To ensure that this feature remains fully functional as we continue to support newer API versions, we should support the DescribeCluster API additionally.
• Redpanda already supports the authorized_operations for the DescribeGroups API (in case its helpful for the implementation)

JIRA Link: CORE-3093

Start with KIP-700 to understand the DescribeCluster v0 contract, then inspect Redpanda's existing authorized_operations support for DescribeGroups. Compare the required response with the metadata v8 behavior described in the issue. Done means DescribeCluster v0 is supported and compliant with the reference configuration, including cluster_authorized_operations.