Enhance error messages in SonataFlowPlatform CR status for knative integration

[jianrongzhang89]

Description

With the implementation for the integration of SonataFlow Operator with Knative: #467, the platform reconciliation logic will log an error message when:

1. the broker used for creating triggers is not created or available, or
2. the SinkBinding has not injected K_SINK into the Job Services deployment
   and the reconciliation will resume after the condition has been resolved.

This follow up issue is to allow the operator to update the SonataFlowPlatform CR status with the corresponding error messages to inform the user that an error has happened.

Implementation ideas

To minimize the impact on the existing logic, it is suggested to use existing condition type "Running" with a Reason like "WaitingKnativeEventing" instead of introducing a new condition type.

[jianrongzhang89]

This is a follow up issue after #467 is merged.