[KED-1874] Move data loader into standalone-app entry point

[richardwestenra]

Description

• Move data-source logic from initial-state: The test datasets aren't necessary in the exported component lib, and are only required when running the full app. So I've moved the data source loading functionality out of the App/initial-state logic
• Replace window.location with document.location: This allows us to remove the typeof window checks, as document is available in build while window isn't.
• Remove conditional window checks on svg-crowbar: These are no longer necessary as of svg-crowbar v0.4.0, updated in [Snyk] Upgrade svg-crowbar from 0.3.1 to 0.6.0 #208
• Load json in src/index.js instead of App component: This simplifies the App component and moves unnecessary logic out of the exported library component
• Allow an argument to be passed to loadJsonData: This will allow external users to load and run it if they wish. e.g.

import KedroViz from '@quantumblack/kedro-viz`;
import loadData from '@quantumblack/kedro-viz/lib/store/load-data';

loadData('/path/to/data.json').then(data => {
  ReactDOM.render(<KedroViz data={data} />, document.getElementById('root'));
});

QA notes

I've changed the componentDidUpdate check to not pay attention to the schema_id. Hopefully this won't change anything. Not sure why I didn't do this before.

Checklist

• Read the contributing guidelines
• Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• Updated the documentation to reflect the code changes
• Added new entries to the RELEASE.md file
• Added tests to cover my changes

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