[aws-cloudwatch-metrics] Support all options in cwagentconfig.json

As per the [docs](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Container-Insights-setup-metrics.html#create-configmap), the `cwagentconfig.json` supports options such as `logs.endpoint_override`, `agent` and `metrics`:

```json
{
"agent": {
"region": "us-east-1"
},
"logs": {
"metrics_collected": {
"kubernetes": {
"cluster_name": "MyCluster",
"metrics_collection_interval": 60
}
},
"force_flush_interval": 5,
"endpoint_override": "logs.us-east-1.amazonaws.com"
},
"metrics": {
"metrics_collected": {
"statsd": {
"service_address": ":8125"
}
}
}
}
```

These options are not currently supported by the chart but should be.

Start with the chart's current handling of cwagentconfig.json and compare it with the AWS configuration documentation linked in the issue. Check how the agent, logs, and metrics options in the example are represented, then verify that the supported configuration covers the documented options and remains valid JSON.

Written by the indexing model from the issue text.