EuiErrorBoundary: converted to Typescript

[ffknob]

Summary

Closes #2661

Converted EuiErrorBoundary to Typescript.

Checklist

• Check against all themes for compatability in both light and dark modes
• Checked in mobile
• Checked in IE11 and Firefox
• Props have proper autodocs
• Added documentation examples
• Added or updated jest tests
• Checked for breaking changes and labeled appropriately
• Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[ffknob]

One thing is, I couldn't convert the component to a Functional Component because React Hooks does not have a hook for componentDidCatch yet.

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[ffknob]

@chandlerprall could you take a look if I got it all?

[chandlerprall]

Updates look good! Few last items from a final pass and this should be good to merge

• added a request around the Error interface
• changelog entry needs to be moved back to the top section, as we just had a release which moved things around
• delete src/components/error_boundary/index.d.ts
• reference to the index.d.ts needs to be removed from

  eui/src/components/index.d.ts

  Line 4 in 3bf9df5

  /// <reference path="./error_boundary/index.d.ts" />

[ffknob]

Think I got it all

[chandlerprall]

jenkins test this

[chandlerprall]

One last request - please export EuiErrorBoundaryProps from src/components/error_boundary/index.ts

[chandlerprall]

Changes LGTM, pulled and tested locally

[chandlerprall]

Thank you once again, @ffknob !