Finalize react native core migration

[nampc1]

Description

This PR builds upon Quoc's PR to improve the code quality of the starter app

Motivation and Context

After discussing with Matteo and Jonathan, we agree that the starter app do not support all WDK modules but only a few features. We also might need to add features in the future, therefore, ensuring high code quality is necessary for easy integration in the future. Plus, this repo's supposed to be a base for developers to build upon or use as a reference, so we need clean and sound codebase.

Scope of change

• Remove all polyfills and redundant dependencies
• Improve network mode by moving all logic to a single hook
• Refactor chain/token config to support new integrations quickly
• Use react-native-core for all crypto operations