Feature Request

Cloudwatch input plugin supports only a single namespace per 1 instance of telegraf.
We would like to ask to have the ability to provide a list of namespaces.

Proposal:

Current behavior:

you can only choose a single namespace to use with the cloudwatch input plugin.

Desired behavior:

having the ability to provide a list of namespaces and get all of their metrics.

  ## Metric Statistic Namespace (required)
  namespace = ["AWS/ELB","AWS/EC2"] 

Use case:

this is important to us because we are using a lot of cloudwatch namespaces - elasticache, ELB, EC2 and more
with current behavior that means we need to have multiple telegraf instances/processes to achieve the same result we had with other tools (grafana datasource / datadog)