Enable other services like Azure ManagedHSM to use the Azure KeyVault client

### Feature Summary

`azure_security_keyvault_keys` crate doesn't work for Azure Managed HSM even though they use the same Rest API as Key Vault.

### Feature Description

Creation of `KeyClient` sets the `scope` is set to `https://vault.azure.net/.default` which I think won't work for Managed HSMs.
https://github.com/Azure/azure-sdk-for-rust/blob/main/sdk/keyvault/azure_security_keyvault_keys/src/generated/clients/key_client.rs

**Ask:** Can the `scopes` or `auth_policy` be taken as an input parameter while creating the `KeyClient`?
We are working on an internal service which uses the same Rest API as Key Vault. Having above capability will help us reuse the client from `azure_security_keyvault_keys` crate.

### Use Case

_No response_

### Alternatives

_No response_

### Additional Context

_No response_