Remove legacyTheme

[shrunyan]

During our transition to the MUI design system we migrated each sub-app independently. This required having the existing theme(legacy) and new theme at the same time. Now that the vast majority of the codebase has been transitioned to the new theme and provider we are ready to remove the legacyTheme and provider.

• Remove legacyTheme usage

  • https://github.com/zesty-io/manager-ui/blob/dev/src/apps/content-editor/src/app/ContentEditor.js#L37
  • https://github.com/zesty-io/manager-ui/blob/dev/src/apps/settings/src/app/App.js#L29
  • https://github.com/zesty-io/manager-ui/blob/dev/src/shell/index.js#L58

• Lift theme provider to top of the app tree root