Update existing APIs and add new APIs for Microsoft.Datadog RP (az datadog)

### Preconditions

- [X] No need to upgrade Python SDK or the Python SDK is ready.

### Related command

_No response_

### Resource Provider

Microsoft.Datadog

### Description of Feature or Work Requested

Update the existing TagRules API with new parameters (automuting and cspm)
Add support for new child RT (monitoredSubscriptions)

### Minimum API Version Required

2023-01-01

### Swagger PR link / SDK link

Public Swagger: https://github.com/Azure/azure-rest-api-specs/tree/main/specification/datadog/resource-manager/Microsoft.Datadog/stable/2023-01-01

PR link for 2023-01-01 version: https://github.com/Azure/azure-rest-api-specs/pull/24495

SDK link: https://github.com/Azure/sdk-release-request/issues/4608#issuecomment-1774591229

### Request Example

_No response_

### Target Date

2023-12-12

### PM Contact

piyushdash

### Engineer Contact

vikotha; dhbansal

### Additional context

_No response_