[AWS::RDS::DBInstance] - [Enhancement] - Support MultiTenant for Oracle CDB

### Name of the resource

AWS::RDS::DBInstance

### Resource name

_No response_

### Description

RDS for Oracle recently supported the Multi tenant configuration for Oracle Database.
https://aws.amazon.com/about-aws/whats-new/2023/11/amazon-rds-oracle-supports-oracle-multitenant/?nc1=h_ls

The configuration can be applied by calling CreateDBInstance API with MultiTenant parameter.
https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html#API_CreateDBInstance_RequestParameters
```
MultiTenant
Specifies whether to use the multi-tenant configuration or the single-tenant configuration (default). This parameter only applies to RDS for Oracle container database (CDB) engines.
```

This is feature request for supporting MultiTenant property in AWS::RDS::DBInstance resource.
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbinstance.html

### Other Details

_No response_

Start with the AWS::RDS::DBInstance resource documentation and the CreateDBInstance API reference linked in the issue; no repository file or test is named. The work is done when the resource supports the MultiTenant property for Oracle CDB instances with behavior matching the API parameter.

Written by the indexing model from the issue text.