Introduce credentials on create and publish calls

Introduce the ability to pass through end user credentials for
authentication/authorization on calls that create and publish calls.

Author: saad-ali

csi.proto

@@ -146,6 +146,11 @@ message CreateVolumeRequest {
   // This field is OPTIONAL. The Plugin is responsible for parsing and
   // validating these parameters. COs will treat these as opaque.
   map<string, string> parameters = 5;
+
+  // End user credentials used to authenticate/authorize volume creation
+  // request.
+  // This field is OPTIONAL.
+  Credentials userCredentials = 6;
 }
 
 message CreateVolumeResponse {
@@ -264,6 +269,18 @@ message VolumeMetadata {
   // each Plugin keeps this information as small as possible.
   map<string, string> values = 1;
 }
+
+// A standard way to encode credential data. The total bytes of the values in
+// the Data field must be less than MaxSecretSize bytes.
+message Credentials {
+  // Data contains the credential data, for example username and password. Each
+  // key must consist of alphanumeric characters, '-', '_' or '.'. The
+  // serialized form of the secret data is a base64 encoded string, representing
+  // the arbitrary (possibly non-string) data value here.
+  // This information is sensitive and should be treated as such (not logged,
+  // etc.)
+  map<string, bytes> Data = 1;
+}
 ////////
 ////////
 message DeleteVolumeRequest {
@@ -309,6 +326,10 @@ message ControllerPublishVolumeRequest {
   // Whether to publish the volume in readonly mode. This field is
   // REQUIRED.
   bool readonly = 5;
+
+  // End user credentials used to authenticate/authorize controller publish
+  // request. This field is OPTIONAL.
+  Credentials userCredentials = 6;
 }
 
 message ControllerPublishVolumeResponse {
@@ -549,6 +570,10 @@ message NodePublishVolumeRequest {
   // Whether to publish the volume in readonly mode. This field is
   // REQUIRED.
   bool readonly = 7;
+
+  // End user credentials used to authenticate/authorize node publish request.
+  // This field is OPTIONAL.
+  Credentials userCredentials = 8;
 }
 
 message NodePublishVolumeResponse {