RFR: 8306021: Add event handler management to EventTarget

[John Hendrikx]

On Wed, 12 Apr 2023 18:19:11 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> This PR adds the following methods to the `EventTarget` interface:
> 1. `addEventHandler`
> 2. `removeEventHandler`
> 3. `addEventFilter`
> 4. `removeEventFilter`

I checked everything, and didn't see any problems; looks good!

-------------

Marked as reviewed by jhendrikx (Committer).

PR Review: https://git.openjdk.org/jfx/pull/1090#pullrequestreview-1386424714