Make Gateway Leadership variables configurable

This PR provides a mechanism to configure the following
Submariner Gateway leader election values
1. leaseDuration
2. renewDeadline
3. retryPeriod

Signed-off-by: Sridhar Gaddam <sgaddam@redhat.com>

submariner/templates/engine-deploy.yaml

@@ -100,6 +100,12 @@ spec:
           value: "{{ .Values.ipsec.ikePort }}"
         - name: CE_IPSEC_NATTPORT
           value: "{{ .Values.ipsec.natPort }}"
+        - name: LEADERSHIP_LEASEDURATION
+          value: "{{ .Values.leadership.leaseDuration }}"
+        - name: LEADERSHIP_RENEWDEADLINE
+          value: "{{ .Values.leadership.renewDeadline }}"
+        - name: LEADERSHIP_RETRYPERIOD
+          value: "{{ .Values.leadership.retryPeriod }}"
         image: {{ .Values.engine.image.repository }}:{{ .Values.engine.image.tag }}
         imagePullPolicy: {{ .Values.engine.image.pullPolicy }}
         name: submariner