Support GitHub app authentication for Sensors

[HaykSHS]

Add GitHub Apps authentication support for Sensors which use github as source, similar to the existing implementation for EventSources (#1372)

We are using git source in sensor triggers to dispatch argo workflow like this and currently can use only token

- template:
     conditions: example
     name: example
     argoWorkflow:
       operation: submit
       source:
         git:
           filePath: workflows/example-workflow.yaml
           url: https://github.com/workflows-example-repo
           branch: main
           creds:
             username:
               name: example-secret
               key: username
             password:
               name: example-secret
               key: token