feat: add RequestContext to PubSubConn (TBD)

Add a wrapper that goes through the standard receiveInternal
processing to match the API of the existing PubSubConn Receive
methods.

Fixes: #592

redis/pubsub.go

@@ -15,6 +15,7 @@
 package redis
 
 import (
+	"context"
 	"errors"
 	"time"
 )
@@ -116,6 +117,12 @@ func (c PubSubConn) ReceiveWithTimeout(timeout time.Duration) interface{} {
 	return c.receiveInternal(ReceiveWithTimeout(c.Conn, timeout))
 }
 
+// ReceiveContext is like Receive, but it allows termination of the receive
+// via a Context.
+func (c PubSubConn) ReceiveContext(ctx context.Context) interface{} {
+	return c.receiveInternal(ReceiveContext(c.Conn, ctx))
+}
+
 func (c PubSubConn) receiveInternal(replyArg interface{}, errArg error) interface{} {
 	reply, err := Values(replyArg, errArg)
 	if err != nil {