Add instance level monitoring agents for RAM and disk volume

### Context

From https://serverfault.com/questions/593431/monitor-aws-ec2-volume-capacity?newreg=89f7a2c993954a9386f1eb49ee32701f:

> The simple answer to this is no. Much like RAM usage (which you will also see no mention of in CloudWatch metrics), disk space cannot be measured outside of the EC2 instance, and requires an OS-level "agent" to report back.

> The issue with agents is privacy (a third party is able to log into your instance), so Amazon has a policy of not breaching this privacy, as doing so would violate a fair number of security certifications, and require Amazon themselves to document, publish and audit the metrics-collection process.

### Problem or idea

RAM usage and disk volume are two metrics which we need to keep an eye on. It'd be nice to have these be viewable for all our client instances in cloudwatch. It'd be even nice if these metrics then made it to the dashboard.

### Solution or next step

Set up the agents to push RAM and disk volume capacity data to cloudwatch.

### New Issue Checklist

- [x] The title is short and descriptive.
- [x] You have explained the context that led you to write this issue.
- [x] You have reported a problem or idea.
- [x] You have proposed a solution or next step.

Review how client EC2 instances are provisioned and how CloudWatch metrics reach the dashboard; no file or test is identified in the issue, so first locate those entry points. Done means RAM usage and disk-volume capacity are reported for all client instances in CloudWatch and exposed on the dashboard.

Written by the indexing model from the issue text.