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/aws-sdk-go-v2/internal/rand/rand.go

@@ -0,0 +1,33 @@
+package rand
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+	"math/big"
+)
+
+func init() {
+	Reader = rand.Reader
+}
+
+// Reader provides a random reader that can reset during testing.
+var Reader io.Reader
+
+var floatMaxBigInt = big.NewInt(1 << 53)
+
+// Float64 returns a float64 read from an io.Reader source. The returned float will be between [0.0, 1.0).
+func Float64(reader io.Reader) (float64, error) {
+	bi, err := rand.Int(reader, floatMaxBigInt)
+	if err != nil {
+		return 0, fmt.Errorf("failed to read random value, %v", err)
+	}
+
+	return float64(bi.Int64()) / (1 << 53), nil
+}
+
+// CryptoRandFloat64 returns a random float64 obtained from the crypto rand
+// source.
+func CryptoRandFloat64() (float64, error) {
+	return Float64(rand.Reader)
+}