[@type/elasticsearch] Change string type to any in connectionClass (#25246)

* Change `connectionClass` type to any

`connectionClass` can not be `string` type. I use my custom `HttpConnector` for sending custom request.

* add describe `HttpConnector` class and write test

* import `HttpConnector` and use it in `connectionClass` config

types/elasticsearch/elasticsearch-tests.ts

@@ -1,10 +1,22 @@
 import * as elasticsearch from "elasticsearch";
+import HttpConnector = require("elasticsearch/src/lib/connectors/http");
+
+class MyHttpConnector extends HttpConnector {
+  constructor(host: any, config: any) {
+    super(host, config);
+  }
+}
 
 let client = new elasticsearch.Client({
   host: 'localhost:9200',
   log: 'trace'
 });
 
+client = new elasticsearch.Client({
+  host: 'localhost:9200',
+  connectionClass: MyHttpConnector
+});
+
 client = new elasticsearch.Client({
   hosts: [
     'box1.server.org',

types/elasticsearch/index.d.ts

@@ -12,6 +12,8 @@
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.2
 
+import HttpConnector = require("./src/lib/connectors/http");
+
 export class Client {
     constructor(params: ConfigOptions);
     cat: Cat;
@@ -111,7 +113,7 @@ export interface ConfigOptions {
     keepAlive?: boolean;
     maxSockets?: number;
     suggestCompression?: boolean;
-    connectionClass?: string;
+    connectionClass?: string | typeof HttpConnector;
     sniffedNodesProtocol?: string;
     ssl?: object;
     selector?: any;

types/elasticsearch/src/lib/connectors/http.d.ts

@@ -0,0 +1,13 @@
+// HttpConnector for elasticsearch
+
+export = HttpConnector;
+
+declare class HttpConnector {
+    constructor(host: any, config: any);
+
+    // onStatusSet(handler: (status: any) => void): void;
+    createAgent(config: any): any;
+    makeAgentConfig(config: any): any;
+    makeReqParams(params: any): any;
+    request(params: any, callback: (error: any, response: any, status: any, headers: any) => void): void;
+}