Template configuration - new coder_agent resource

[defelmnq]

The template configuration issue includes all the components required in order for coderd to read and access the OOM & OOD configuration.

As per the RFC, the new component to read from the agent block look like :

resource "coder_agent" "blah" {
	resource_monitoring { 
		memory = {
		  enabled = true
		  threshold = 50
	  }
	  volumes = {
		  "/home/user": {
				enabled = true
				threshold = 85		  
		  }
		  "/home/coder": {    // as enabled is false, it will not be monitored.
			  enabled = false
			  threshold = 90
		  }
	  }
	}
}

This logic is done inside the ConvertState function https://github.com/coder/coder/blob/630fd7c0a1ee44fa6ce61ac9cb4c76842dc247dd/provisioner/terraform/resources.go#L143

The parsed configuration then has to be stored into the DB for further usage.

The scope of this issue stops when the data are inserted in the database - with the associated methods available to fetch it.