Add spot tags as resource tags of instances and volumes in launch template

According to the APIReference:
<https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_LaunchTemplateTagSpecificationRequest.html>,
the resource types `instance` and `volume` support tagging on creation.
It is useful to add the spot tags here as it should be more reliable
than tagging them after the spot request is fulfilled as we currently
do.

builder/amazon/common/step_run_spot_instance.go

@@ -260,6 +260,16 @@ func (s *StepRunSpotInstance) Run(ctx context.Context, state multistep.StateBag)
 				Tags:         spotTags,
 			},
 		}
+		launchTemplate.LaunchTemplateData.TagSpecifications = []*ec2.LaunchTemplateTagSpecificationRequest{
+			{
+				ResourceType: aws.String("instance"),
+				Tags:         spotTags,
+			},
+			{
+				ResourceType: aws.String("volume"),
+				Tags:         spotTags,
+			},
+		}
 	}
 
 	// Tell EC2 to create the template