rbd: add aws-sts-metdata encryption type

With Amazon STS and kubernetes cluster is configured with
OIDC identity provider, credentials to access Amazon KMS
can be fetched using oidc-token(serviceaccount token).
Each tenant/namespace needs to create a secret with aws region,
role and CMK ARN.
Ceph-CSI will assume the given role with oidc token and access
aws KMS, with given CMK to encrypt/decrypt DEK which will stored
in the image metdata.

Refer: https://docs.aws.amazon.com/STS/latest/APIReference/welcome.html
Resolves: #2879

Signed-off-by: Rakshith R <rar@redhat.com>

vendor/github.com/aws/smithy-go/document/errors.go

@@ -0,0 +1,75 @@
+package document
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// UnmarshalTypeError is an error type representing an error
+// unmarshaling a Smithy document to a Go value type. This is different
+// from UnmarshalError in that it does not wrap an underlying error type.
+type UnmarshalTypeError struct {
+	Value string
+	Type  reflect.Type
+}
+
+// Error returns the string representation of the error.
+// Satisfying the error interface.
+func (e *UnmarshalTypeError) Error() string {
+	return fmt.Sprintf("unmarshal failed, cannot unmarshal %s into Go value type %s",
+		e.Value, e.Type.String())
+}
+
+// An InvalidUnmarshalError is an error type representing an invalid type
+// encountered while unmarshaling a Smithy document to a Go value type.
+type InvalidUnmarshalError struct {
+	Type reflect.Type
+}
+
+// Error returns the string representation of the error.
+// Satisfying the error interface.
+func (e *InvalidUnmarshalError) Error() string {
+	var msg string
+	if e.Type == nil {
+		msg = "cannot unmarshal to nil value"
+	} else if e.Type.Kind() != reflect.Ptr {
+		msg = fmt.Sprintf("cannot unmarshal to non-pointer value, got %s", e.Type.String())
+	} else {
+		msg = fmt.Sprintf("cannot unmarshal to nil value, %s", e.Type.String())
+	}
+
+	return fmt.Sprintf("unmarshal failed, %s", msg)
+}
+
+// An UnmarshalError wraps an error that occurred while unmarshaling a
+// Smithy document into a Go type. This is different from
+// UnmarshalTypeError in that it wraps the underlying error that occurred.
+type UnmarshalError struct {
+	Err   error
+	Value string
+	Type  reflect.Type
+}
+
+// Unwrap returns the underlying unmarshaling error
+func (e *UnmarshalError) Unwrap() error {
+	return e.Err
+}
+
+// Error returns the string representation of the error.
+// Satisfying the error interface.
+func (e *UnmarshalError) Error() string {
+	return fmt.Sprintf("unmarshal failed, cannot unmarshal %q into %s, %v",
+		e.Value, e.Type.String(), e.Err)
+}
+
+// An InvalidMarshalError is an error type representing an error
+// occurring when marshaling a Go value type.
+type InvalidMarshalError struct {
+	Message string
+}
+
+// Error returns the string representation of the error.
+// Satisfying the error interface.
+func (e *InvalidMarshalError) Error() string {
+	return fmt.Sprintf("marshal failed, %s", e.Message)
+}