fix: EventObj cannot be imported

[heggiG]

Fixes the EventObj type not being exported.

See #427

[EkimChau]

Hello @heggiG,
Thank you for your code contribution to this project, Tiny would like to publish and acknowledge your code contribution to the TinyMCE-Angular open source project in the next release. For Tiny to proceed, we will need permissions from you to use your code. Could you email [email protected] with the subject CLA request for heggiG. Our legal team will send you a Contributors License Agreement (CLA) that gives Tiny permissions to use your code.

Thanks again for your contributions

[tiny-ben-tran]

@heggiG Looks good. Please add a changelog entry under Unreleased heading