Konnect CRDs: rename `KonnectEventControlPlane` to `KonnectEventGateway` to match UI/API

### Problem statement

`KonnectEventControlPlane` CRD has been found to be inconsistent with UI and API naming conventions.


### Proposed solution

Rename `KonnectEventControlPlane` to `KonnectEventGateway`

### Anything else

x-ref slack thread: https://kongstrong.slack.com/archives/C0APS0S3ELF/p1776261515007989?thread_ts=1776249962.474109&cid=C0APS0S3ELF