Determine if ARM/RP namespace is new (no existing SDKs) in the onboard feature

Today the new ARM namespace field in the Triage ADO requires manual input. In order for onboarding of products to be 100% self-service, the new ARM namespace field value should be confirmed during the onboard feature UI flow.

Dependency on - https://github.com/Azure/azure-sdk-tools/issues/7503

**Initial thoughts on design**
- When the RP name + resource type features is re-designed, we can query our dataverse to see if the RP name exists. https://github.com/Azure/azure-sdk-tools/issues/7503
- If ARM/RP name exists in the release planner data, we can display message. "The ARM/RP is associated with existing products. Please identify the resource type for the product? Drop-down list of resource types associated with the RP. Have an option for new resource types not yet added to service tree. Perhaps a button that is selected.
- If the ARM/RP namespace is found, then it could be that there are existing SDKs. In the user interface, if the ARM/RP namespace is found, we could display information and have user confirm. For example, The ARM/RP namespace was found, will this product be contributing to existing SDKs (new SDK version)?
- If ARM/RP name is not found in the release planner data, then ask the user if it is a new ARM/RP namespace? If it is a new ARM/RP namespace, then it will be new initial SDKs. There would not be a need to ask then the user if there are existing SDKs.