[BUG] FormBuilder is not using namespace when handling events

[nathanaelbice]

Environment

Please provide as many details as you can:
When emitting an event from within a form, the FormBuilder component is not properly handling the case that a custom namespace is set in the options. The emit function consults the options.namespace setting to prefix the event type, but the FormBuilder component only ever checks for "Formio".

• Hosting type
  • [] Form.io
  • Local deployment
    • Version: N/A
• Formio.js version: 4.0.0
• Frontend framework: Vue.js
• Browser: Chrome
• Browser version: 80.0.3987.132

Steps to Reproduce

1. Emit a custom event from inside the formbuilder
2. Note that it doesn't bubble outside of the builder

Expected behavior

The event would be re-thrown into Vue

Observed behavior

The event is swallowed.