fix(typescript): remove incorrect file extensions (#20194)

* fix(typescript): remove incorrect file extensions

url, http, and https are Node.js core modules, and form-data
should be loaded using a bare specifier. This commit removes
the file extensions from these imports.

* update samples

modules/openapi-generator/src/main/resources/typescript/http/http.mustache

@@ -1,10 +1,10 @@
 {{#platforms}}
 {{#node}}
 // TODO: evaluate if we can easily get rid of this library
-import {{^supportsES6}}* as{{/supportsES6}} FormData from "form-data{{importFileExtension}}";
-import { URL, URLSearchParams } from 'url{{importFileExtension}}';
-import * as http from 'http{{importFileExtension}}';
-import * as https from 'https{{importFileExtension}}';
+import {{^supportsES6}}* as{{/supportsES6}} FormData from "form-data";
+import { URL, URLSearchParams } from 'url';
+import * as http from 'http';
+import * as https from 'https';
 {{/node}}
 {{/platforms}}
 import { Observable, from } from {{#useRxJS}}'rxjs'{{/useRxJS}}{{^useRxJS}}'../rxjsStub{{importFileExtension}}'{{/useRxJS}};
@@ -169,7 +169,7 @@ export class RequestContext {
     }
     {{#platforms}}
     {{#node}}
-    
+
     public setAgent(agent: http.Agent | https.Agent) {
         this.agent = agent;
     }