kms: add context.Context to KMS API calls (#15327)

This commit adds a `context.Context` to the
the KMS `{Stat, CreateKey, GenerateKey}` API
calls.

The context will be used to terminate external calls
as soon as the client requests gets canceled.

A follow-up PR will add a `context.Context` to
the remaining `DecryptKey` API call.

Signed-off-by: Andreas Auernhammer <hi@aead.dev>

cmd/config-encrypted.go

@@ -70,7 +70,7 @@ func migrateIAMConfigsEtcdToEncrypted(ctx context.Context, client *etcd.Client)
 	}
 
 	if encrypted && GlobalKMS != nil {
-		stat, err := GlobalKMS.Stat()
+		stat, err := GlobalKMS.Stat(ctx)
 		if err != nil {
 			return err
 		}
@@ -139,7 +139,7 @@ func migrateConfigPrefixToEncrypted(objAPI ObjectLayer, encrypted bool) error {
 		return nil
 	}
 	if encrypted && GlobalKMS != nil {
-		stat, err := GlobalKMS.Stat()
+		stat, err := GlobalKMS.Stat(context.Background())
 		if err != nil {
 			return err
 		}