Listening for DOMContent loaded only if page state is 'loading' for oauth2-redirect.html

[Bogdan-Hasanov]

Description

Forcing execution of the oauth-redirect.html run function after DOMContentLoaded is fired.

Motivation and Context

I've encountered an issue trying to authorize to the API that is hosted behind CloudFlare and is using Cloudflare’s Browser Insights which injects beacon.js file which finishes loading after DOM is loaded. So the run function couldn't be executed when DOMContentLoaded event is fired.
This change uses code from StackOverflow question answer

How Has This Been Tested?

I was redirected having Cloudflare's beacon.js injected on the deployed server

Screenshots (if appropriate):

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[tim-lai]

@Bogdan-Hasanov PR merged! Thanks for the contribution!