Allow users to set resources as part of podtemplate

[savitaashture]

Changes

Issue: #762

Added changes to allow resource information as part of eventlistener.

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• Includes tests (if functionality changed/added)
• Includes docs (if user facing)
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Release Notes

Now trigger allow users to specify their resource information in eventlistener

apiVersion: triggers.tekton.dev/v1alpha1
kind: EventListener
metadata:
  name: github-listener-interceptor
spec:
  ...
  resources:
    kubernetesResource:
      spec:
        template:
          spec:
            serviceAccountName: tekton-triggers-github-sa
            containers:
              - resources:
                  requests:
                    memory: "64Mi"
                    cpu: "250m"
                  limits:
                    memory: "128Mi"
                    cpu: "500m"

[dibyom]

/lgtm

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