[Feature]: A quick way to update `AzProviderHubResourceTypeRegistration`

### Description of the new feature

For common RPaas resource type registration update scenario, we need to add a new region endpoint. Currently, we need to first get existing properties with `Get-AzProviderHubResourceTypeRegistration`, then modify `Endpoints` property and input all other properties to each option of `New-AzProviderHubResourceTypeRegistration` to do the update.

Is there a convenient quick way to use result of `Get-AzProviderHubResourceTypeRegistration`, modify Endpoints property, then use it directly as input for `New-AzProviderHubResourceTypeRegistration`?

### Proposed implementation details (optional)

_No response_

Start with the Get-AzProviderHubResourceTypeRegistration and New-AzProviderHubResourceTypeRegistration entry points, focusing on their properties and parameter handling. Reproduce the existing workflow, then determine how a Get result with a modified Endpoints property could be accepted for registration update. Done means the common update scenario works without manually supplying every other property, with coverage for the new input behavior.

Written by the indexing model from the issue text.