Missing imagePullSecrets field from aws-cloudwatch-metrics helm chart

**Describe the bug**
The aws-cloudwatch-metrics chart does not have the **imagePullSecrets** field to pull the docker image from private registries.

**Steps to reproduce**

**Expected outcome**
The chart allows to specify the **imagePullSecrets** field as it is done for the other charts (i.e. aws-for-fluent-bit).

**Environment**

* Chart name: aws-cloudwatch-metrics
* Chart version: 0.0.6
* Kubernetes version: N/A (any)
* Using EKS (yes/no), if so version? N/A (any)

**Additional Context**:

Inspect the aws-cloudwatch-metrics Helm chart and compare its image configuration with the aws-for-fluent-bit chart mentioned in the issue. Verify the rendered chart accepts imagePullSecrets for the private registry use case; done means the field can be specified for chart version 0.0.6.

Written by the indexing model from the issue text.