chore: track workspace resource monitors in telemetry (#16776)

Addresses https://github.com/coder/nexus/issues/195. Specifically, just
the "tracking templates" requirement:

> ## Tracking in templates
> To enable resource alerts, a user must add the resource_monitoring
block to a template's coder_agent resource. We'd like to track if
customers have any resource monitoring enabled on a per-deployment
basis. Even better, we could identify which templates are using resource
monitoring.

coderd/database/queries/workspaceagentresourcemonitors.sql

@@ -1,3 +1,19 @@
+-- name: FetchVolumesResourceMonitorsUpdatedAfter :many
+SELECT
+	*
+FROM
+	workspace_agent_volume_resource_monitors
+WHERE
+	updated_at > $1;
+
+-- name: FetchMemoryResourceMonitorsUpdatedAfter :many
+SELECT
+	*
+FROM
+	workspace_agent_memory_resource_monitors
+WHERE
+	updated_at > $1;
+
 -- name: FetchMemoryResourceMonitorsByAgentID :one
 SELECT
 	*