[AWS::MediaPackageV2::OriginEndpoint] - [Missing ISM container and MSS manifest support]

### Name of the resource

AWS::MediaPackageV2::OriginEndpoint

### Resource name

_No response_

### Description

### Use Case

The `AWS::MediaPackageV2::OriginEndpoint` resource is missing support for the `ISM` container type and `MssManifests` configuration.

These options are already available through the AWS Console and API, but are not exposed in CloudFormation. This limits our ability to manage these endpoints via Infrastructure as Code (IaC) and prevents us from using the `awscc` Terraform provider for full automation.

### Request

Please add support for the following:

- `ContainerType: ISM`
- `MssManifests`: configuration block for Smooth Streaming manifests

These features are important for delivering Smooth Streaming content and are fully supported in the MediaPackage V2 API.

### Impact

- Breaks parity between AWS Console/API and CloudFormation
- Prevents automated deployment of ISM endpoints
- Affects Terraform users relying on the awscc provider

### Other Details

_No response_

Start by reviewing the AWS::MediaPackageV2::OriginEndpoint resource coverage and the MediaPackage V2 API options described in this issue. Confirm how ContainerType: ISM and the MssManifests configuration block should be represented, then verify that CloudFormation and the awscc Terraform provider expose both options. Done means ISM endpoints and Smooth Streaming manifests can be configured through infrastructure as code.

Written by the indexing model from the issue text.