support topologySpreadConstraints in Deployment config

[jmazzitelli]

part of : kiali/kiali#5614

To quickly test:

1. Build the charts: make build-helm-charts
2. Set some topology spread constraints to see that it gets into the deployment yaml:

helm template -n istio-system \
  --show-only templates/deployment.yaml \
  --set deployment.topology_spread_constraints[0].maxSkew=1 \
  --set deployment.topology_spread_constraints[0].whenUnsatisfiable=DoNotSchedule \
  --set deployment.topology_spread_constraints[0].topologyKey=kubernetes.io/hostname \
  kiali-server \
  _output/charts/kiali-server-*.tgz

3. See that the spec.topologySpreadConstraints yaml is in the yaml
4. Now see that if you do not specify topology spread constraints, the yaml does not show anything:

helm template -n istio-system --show-only templates/deployment.yaml kiali-server _output/charts/kiali-server-*.tgz

[jshaughn]

LG