feat: add connection statistics for workspace agents (#6469)

* fix: don't make session counts cumulative

This made for some weird tracking... we want the point-in-time
number of counts!

* Add databasefake query for getting agent stats

* Add deployment stats endpoint

* The query... works?!?

* Fix aggregation query

* Select from multiple tables instead

* Fix continuous stats

* Increase period of stat refreshes

* Add workspace counts to deployment stats

* fmt

* Add a slight bit of responsiveness

* Fix template version editor overflow

* Add refresh button

* Fix font family on button

* Fix latest stat being reported

* Revert agent conn stats

* Fix linting error

* Fix tests

* Fix gen

* Fix migrations

* Block on sending stat updates

* Add test fixtures

* Fix response structure

* make gen

coderd/deployment.go

@@ -0,0 +1,61 @@
+package coderd
+
+import (
+	"net/http"
+
+	"github.com/coder/coder/coderd/httpapi"
+	"github.com/coder/coder/coderd/rbac"
+	"github.com/coder/coder/codersdk"
+)
+
+// @Summary Get deployment config
+// @ID get-deployment-config
+// @Security CoderSessionToken
+// @Produce json
+// @Tags General
+// @Success 200 {object} codersdk.DeploymentConfig
+// @Router /deployment/config [get]
+func (api *API) deploymentValues(rw http.ResponseWriter, r *http.Request) {
+	if !api.Authorize(r, rbac.ActionRead, rbac.ResourceDeploymentValues) {
+		httpapi.Forbidden(rw)
+		return
+	}
+
+	values, err := api.DeploymentValues.WithoutSecrets()
+	if err != nil {
+		httpapi.InternalServerError(rw, err)
+		return
+	}
+
+	httpapi.Write(
+		r.Context(), rw, http.StatusOK,
+		codersdk.DeploymentConfig{
+			Values:  values,
+			Options: values.Options(),
+		},
+	)
+}
+
+// @Summary Get deployment stats
+// @ID get-deployment-stats
+// @Security CoderSessionToken
+// @Produce json
+// @Tags General
+// @Success 200 {object} codersdk.DeploymentStats
+// @Router /deployment/stats [get]
+func (api *API) deploymentStats(rw http.ResponseWriter, r *http.Request) {
+	if !api.Authorize(r, rbac.ActionRead, rbac.ResourceDeploymentStats) {
+		httpapi.Forbidden(rw)
+		return
+	}
+
+	stats, ok := api.metricsCache.DeploymentStats()
+	if !ok {
+		httpapi.Write(r.Context(), rw, http.StatusBadRequest, codersdk.Response{
+			Message: "Deployment stats are still processing!",
+		})
+		return
+	}
+
+	httpapi.Write(r.Context(), rw, http.StatusOK, stats)
+}