[Consistency] BackupClient should not accept Azure::Core::Url as input param, but rather std::string.

[ahsonkhan]

We recently introduced BackupClient in azure-security-keyvault-administration: #5744

It should accept input urls as std::string, instead of Azure::Core::Url following the consistent pattern from the rest of the SDK clients. When the user needs to pass a blobContainerUrl parameter, they would get it from the GetUrl() method, which returns the std::string:

azure-sdk-for-cpp/sdk/storage/azure-storage-blobs/inc/azure/storage/blobs/blob_container_client.hpp

Line 124 in 7e92467

std::string GetUrl() const { return m_blobContainerUrl.GetAbsoluteUrl(); }

Calling out some examples, but we should evaluate all cases:

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-administration/inc/azure/keyvault/administration/backup_client.hpp

Lines 74 to 77 in 7e92467

	Response<BackupOperation> FullBackup(
	Azure::Core::Url const& blobContainerUrl,
	Models::SasTokenParameter const& sasToken,
	Core::Context const& context = {});

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-administration/inc/azure/keyvault/administration/backup_client.hpp

Lines 102 to 106 in 7e92467

	Response<BackupOperation> FullRestore(
	Azure::Core::Url const& blobContainerUrl,
	std::string folderToRestore,
	Models::SasTokenParameter const& sasToken,
	Core::Context const& context = {});

Note, the BackupClient ctor is following the pattern from across KeyVault, as expected, for the vaultUrl:

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-administration/inc/azure/keyvault/administration/backup_client.hpp

Lines 57 to 60 in 7e92467

	explicit BackupClient(
	std::string const& vaultUrl,
	std::shared_ptr<Core::Credentials::TokenCredential const> credential,
	BackupClientOptions options = BackupClientOptions());

[ahsonkhan]

cc @RickWinter just a heads up for whenever we plan to GA KeyVault Administration