feat: add workspace agent stat reporting to telemetry (#6577)

This aggregates stats periodically and sends them by agent ID to
our telemetry server. It should help us identify which editors are
primarily in use.

coderd/telemetry/telemetry_test.go

@@ -67,6 +67,7 @@ func TestTelemetry(t *testing.T) {
 		_ = dbgen.WorkspaceResource(t, db, database.WorkspaceResource{
 			Transition: database.WorkspaceTransitionStart,
 		})
+		_ = dbgen.WorkspaceAgentStat(t, db, database.WorkspaceAgentStat{})
 		_, err = db.InsertLicense(ctx, database.InsertLicenseParams{
 			UploadedAt: database.Now(),
 			JWT:        "",
@@ -86,6 +87,7 @@ func TestTelemetry(t *testing.T) {
 		require.Len(t, snapshot.WorkspaceAgents, 1)
 		require.Len(t, snapshot.WorkspaceBuilds, 1)
 		require.Len(t, snapshot.WorkspaceResources, 1)
+		require.Len(t, snapshot.WorkspaceAgentStats, 1)
 	})
 	t.Run("HashedEmail", func(t *testing.T) {
 		t.Parallel()