Generated API Gateway SDK does not provide a way to pass http headers

Consider an API Gateway endpoint with a required HTTP request header for Accept-Language (e.g OpenAPI def):
```
"paths": {
"/jobs/{id}": {
"get": {
"operationId": "getById",
"produces": [
"application/json"
],
"parameters": [
{
"name": "Accept-Language",
"in": "header",
"required": true,
"type": "string"
}
```

The generated Ruby SDK does not provide a way to pass the required parameter to the endpoint.

### Gem name ('aws-sdk', 'aws-sdk-resources' or service gems like 'aws-sdk-s3') and its version
API Gateway generated aws-sdk-v3

Thanks,