fix: set DataPlane's extensions through GatewayConfiguration

[pmalek]

What this PR does / why we need it:

#453 missed configuring extensions for Gateway's DataPlane so this is adding the missing bit.

Which issue this PR fixes

Fixes #

Special notes for your reviewer:

This requires tests to be added.

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect significant changes

[mlavacca]

I have been exploring this issue when implementing #453, but it's not as straightforward as it might look. If we provision the DataPlane with Konnect configuration and a regular ControlPlane, we end up with KIC not being able to push configuration to the DataPlane (as it is not configured to accept the config from KIC), and it never gets ready. We likely need to improve the Controlplane as well to be able to receive KonnectExtension, to configure it to work in Konnect.

I've just created #874 to track this effort

[pmalek]

I have been exploring this issue when implementing #453, but it's not as straightforward as it might look. If we provision the DataPlane with Konnect configuration and a regular ControlPlane, we end up with KIC not being able to push configuration to the DataPlane (as it is not configured to accept the config from KIC), and it never gets ready. We likely need to improve the Controlplane as well to be able to receive KonnectExtension, to configure it to work in Konnect.

I've just created #874 to track this effort

Ah indeed. I missed this because I only glanced at the fact that this field is not set for DataPlanes when deploying with Gateway.

I was also thinking about making ControlPlane able to get the Konnect extension. Thanks for creating the issue for this one 🙇