Updated abort behavior (#1141)

* Updated abort behavior

- Support for aborting a request with the promise api
- Aborting a request will cause a RequestAbortedError
- Normalized Connection class errors, now every error returned is
wrapped by the client errors constructors

* Updated test

* Updated docs

* Updated code generation script

* Renamed test

* Code coverage

* Avoid calling twice transport.request

lib/errors.d.ts

@@ -59,3 +59,10 @@ export declare class ResponseError extends ElasticsearchClientError {
   headers: Record<string, any>;
   constructor(meta: ApiResponse);
 }
+
+export declare class RequestAbortedError extends ElasticsearchClientError {
+  name: string;
+  message: string;
+  meta: ApiResponse;
+  constructor(message: string, meta: ApiResponse);
+}