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/timeconv/duration.go

@@ -0,0 +1,13 @@
+package timeconv
+
+import "time"
+
+// FloatSecondsDur converts a fractional seconds to duration.
+func FloatSecondsDur(v float64) time.Duration {
+	return time.Duration(v * float64(time.Second))
+}
+
+// DurSecondsFloat converts a duration into fractional seconds.
+func DurSecondsFloat(d time.Duration) float64 {
+	return float64(d) / float64(time.Second)
+}