chore(demo app): Fix build of demo app and center graph initially

[jeff-phillips-18]

Description

The demo application does not build due to:

ERROR in src/App.tsx:38:19
TS2686: 'React' refers to a UMD global, but the current file is a module. Consider adding an import instead.
    36 | }
    37 |
  > 38 | class App extends React.Component<{}, AppState> {

Fixing this issue reveals that the graph is no longer being centered in the TopologyPackage demo.

This PR fixes the build issue and fixes centering the graph in the demo

Type of change

• Other (please describe): Fixes the example/demo application

[patternfly-build]

Preview: https://react-topology-pr-topology-284.surge.sh

[jenny-s51]

Great work @jeff-phillips-18 ! Graph centering looks awesome - I'm still seeing a couple of errors being thrown by webpack in the demo-app build which we can resolve with these two quick fixes - PRed your changes: jeff-phillips-18#2

[jenny-s51]

Thanks @jeff-phillips-18 ! Tested in docs workspace and demo app. Graph centering now works as expected and demo app builds successfully. LGTM

[github-actions]

🎉 This PR is included in version 6.3.0-prerelease.2 🎉

The release is available on:

• GitHub release
• npm package (@prerelease dist-tag)

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