Replace the deprecated eslint-loader with eslint-webpack-plugin in Identity Apps

[brionmario]

Is your suggestion related to an experience ? Please describe.
eslint-loader was deprecated in favor of eslint-webpack-plugin (see https://github.com/webpack-contrib/eslint-loader).
Some advantages over eslint-loader include the reuse of the ESLint cache and improved lint performance (see https://github.com/webpack-contrib/eslint-webpack-plugin#about-plugin).

Describe the improvement
Replace the deprecated eslint-loader with eslint-webpack-plugin.

Additional context
Tried to migrate but there seems to be few issues with the new eslint-webpack-plugin.

1. Recompile time significantly increased when migrated.(WDS significant increase in recompile time after migrating from eslint-loader webpack-contrib/eslint-webpack-plugin#20)
   • Used the lintDirtyModulesOnly as suggested but that caused errors to not being recognised.
2. File names and path are not shown properly which makes it hard to figure out which file has the errors. A custom formatter has to be written to overcome the issue. (Replace deprecated eslint-loader by eslint-webpack-plugin facebook/create-react-app#9751 (comment))

Issues to keep an eye out for:

• eslint-webpack-plugin is 2.5 times slower than eslint-loader  webpack-contrib/eslint-webpack-plugin#30
• WDS significant increase in recompile time after migrating from eslint-loader webpack-contrib/eslint-webpack-plugin#20
• Option to run only on files in module graph webpack-contrib/eslint-webpack-plugin#23

NOTE: Only do the migration when the plugin is stable.

[brionmario]

Fixed with wso2/identity-apps#1924