[Keras 3 OpenVINO backend]: Support cond operator and hinge losses

[goyaladitya05]

Request Description

This issue tracks adding support for cond operator, and hinge losses (which required cond operator) for the Keras OpenVINO backend.
The operator is currently not implemented in keras/backend/openvino, limiting parity for this backend.

I will submit a PR implementing this and enable the corresponding tests.

Ref: #34017

Feature Use Case

No response

Issue submission checklist

• The feature request or improvement must be related to OpenVINO