fix: Prevents useEffect double render in React18 StrictMode

[trevoring-okta]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Adding Tests
• Build related changes
• CI related changes
• Documentation changes
• Other... Please describe:

What is the current behavior?

In React18 StrictMode, useEffects run twice on component mount. This causes handleLoginRedirect() to run twice in the LoginCallback component, triggering an AuthSdkError from auth-js.

Issue Number: #263

Internal Ref: OKTA-635977

What is the new behavior?

Adds a top-level variable in LoginCallback that prevents handleLoginRedirect() from running twice. Solution follows React18 guidance

Does this PR introduce a breaking change?

• Yes
• No

Other information

• Unit testing required bumping jest to 29.x to have access to jest.isolateModulesAsync()
• e2e testing required bumping the test-harness-app to React18 and adding a new start:dev script (as well as a .env.development file) to enable testing on a development build since this bug only exists in React18 dev mode. The v6-app was also bumped to maintain parity

[stormsilver]

The pipeline for publishing this appears to have failed: https://github.com/okta/okta-react/actions/runs/6088093926/job/16518033829

The currently available version on NPM is still 6.7.0.

[eddiemonge]

@trevoring-okta