Update Azure SDK and support additional authentication schemes

Microsoft has updated the golang Azure SDK significantly.  Update the
azure storage driver to use the new SDK.  Add support for client
secret and MSI authentication schemes in addition to shared key
authentication.

Implement rootDirectory support for the azure storage driver to mirror
the S3 driver.

Signed-off-by: Kirat Singh <kirat.singh@beacon.io>

Co-authored-by: Cory Snider <corhere@gmail.com>

vendor/github.com/Azure/azure-sdk-for-go/sdk/azidentity/logging.go

@@ -0,0 +1,30 @@
+//go:build go1.18
+// +build go1.18
+
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azidentity
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+	"github.com/Azure/azure-sdk-for-go/sdk/internal/log"
+)
+
+// EventAuthentication entries contain information about authentication.
+// This includes information like the names of environment variables
+// used when obtaining credentials and the type of credential used.
+const EventAuthentication log.Event = "Authentication"
+
+func logGetTokenSuccess(cred azcore.TokenCredential, opts policy.TokenRequestOptions) {
+	if !log.Should(EventAuthentication) {
+		return
+	}
+	scope := strings.Join(opts.Scopes, ", ")
+	msg := fmt.Sprintf("%T.GetToken() acquired a token for scope %s\n", cred, scope)
+	log.Write(EventAuthentication, msg)
+}