[BUG] Plugin helpers fix related to fs promises module (#2486)

In Node v10, there was no dedicated module for fs/promises.
Causing the plugin helpers to fail while building out plugins.

Solved by importing promises from fs then using the desired
methods.

Issue Resolved:
#2485

Signed-off-by: Kawika Avilla <kavilla414@gmail.com>

Author: kavilla

CHANGELOG.md

@@ -35,6 +35,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### 🐛 Bug Fixes
 
+* Plugin helpers fix related to fs promises module ([#2486](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2486))
+
 ### 🚞 Infrastructure
 
 ### 📝 Documentation

packages/osd-plugin-helpers/src/tasks/update_versions.ts

@@ -4,11 +4,13 @@
  */
 
 // @ts-ignore
-import { readFile, writeFile } from 'fs/promises';
+import { promises } from 'fs';
 import path from 'path';
 import { createFailError } from '@osd/dev-utils';
 import { FileUpdateContext, ObjectUpdateContext, VersionContext } from '../contexts';
 
+const { readFile, writeFile } = promises;
+
 export async function updateVersions({
   log,
   sourceDir,