Allow Filebeat deployment as a StatefulSet in current or new Helm Chart

[sboulkour]

Describe the enhancement:
Current Helm chart only allow the deployment of FileBeat as a daemonSet. This is perfect to gather logs from K8s cluster itself but doesn't fit the other use case.

Describe a specific use case for the enhancement or feature:
In my use case, a deploy a set of FileBeat instances per AWS module to activate. One for ELB access logs, one for S3 access logs etc. For each instance I want one to three pods max, not one pod per node in my Kubernetes cluster.

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[masci]

Closing as we have a similar issue in the Helm chart repo elastic/helm-charts#821 let's move the discussion there.