[AWS::Redshift::ClusterSubnetGroup] - [Coverage] - Missing ClusterSubnetGroupName property

### Name of the resource

AWS::Redshift::ClusterSubnetGroup

### Resource name

_No response_

### Description

When creating a Redshift cluster subnet group (outside of CloudFormation), the group name is one of the allowed properties. CloudFormation doesn't have this as an available option, leading to groups being created with auto-generated names rather than desired, intentional names.

### Other Details

Also of note, in my simple test, `ClusterSubnetGroupName` was not rejected as an invalid property. However the group was still created with an auto-generated name and not the value passed in via `ClusterSubnetGroupName`

Start by locating the coverage entry for AWS::Redshift::ClusterSubnetGroup and checking how its properties are represented. Verify the handling of ClusterSubnetGroupName against the reported behavior, then confirm that a supplied name is accepted and preserved instead of an auto-generated name.

Written by the indexing model from the issue text.