(aws-redshift-alpha): (provide the ability to reduce schema privileges for a user)

### Describe the feature

The User construct in the library creates a new user for the Redshift database. This user has no Table access privileges and there is a good mechanism to add only the access desired. But the user by default has Create privileges on the schema (e.g. - the user can create new tables in the schema and have full access to those new tables. It would be nice to have a way to prevent this, either:

* Create the user with no schema privileges and add a addSchemaPrivileges() method to User
* Specify user privileges in the schema in the props
* Allow the revocation of default privileges after creation (almost didn't include this, I don't think it's a very good approach)

The first option seems most in line with patterns you have already established in the library - although I'm not sure if it is invalidated by some subtlety in Redshift that I'm missing.

### Use Case

We're writing an aws-firehose-redshift construct in the AWS Solutions Constructs library. One of our benefits is implementing best practices for each service and between services - in this case it is recommended that the Redshift user assumed by Firehose be limited to INSERT only privileges and only on the destination table.

### Proposed Solution

I think I did this up above...

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.37.1-alpha.0

### Environment details (OS name and version, etc.)

macOS Monterey 12.6

Start by locating the aws-redshift-alpha User construct and its existing schema and table privilege APIs. Review how Redshift assigns default schema privileges and compare the proposed approaches; done means the construct can restrict a Firehose user's access to the intended destination-table privileges, with tests covering the resulting permissions.

Written by the indexing model from the issue text.