headerClientContext should match aws-sdk-go-v2

[nalbion]

Is your feature request related to a problem? Please describe.

aws-sdk-go-v2 sets the header "X-Amz-Client-Context":

	if v.ClientContext != nil && len(*v.ClientContext) > 0 {
		locationName := "X-Amz-Client-Context"
		encoder.SetHeader(locationName).String(*v.ClientContext)
	}

https://github.com/aws/aws-sdk-go-v2/blob/main/service/lambda/serializers.go#L2815C19-L2815C38

but this library reads the header "Lambda-Runtime-Client-Context"

	headerClientContext      = "Lambda-Runtime-Client-Context"
...
func parseClientContext(invoke *invoke, out *lambdacontext.ClientContext) error {
	clientContextJSON := invoke.headers.Get(headerClientContext)
	if clientContextJSON != "" {
		if err := json.Unmarshal([]byte(clientContextJSON), out); err != nil {
			return fmt.Errorf("failed to unmarshal client context json: %v", err)
		}
	}
	return nil
}

https://github.com/aws/aws-lambda-go/blob/main/lambda/invoke_loop.go#L150
https://github.com/aws/aws-lambda-go/blob/main/lambda/runtime_api_client.go#L23C2-L23C21