chore: break down dbauthz.System into smaller roles (#6218)

- rbac: export rbac.Permissions
- dbauthz: move GetDeploymentDAUs, GetTemplateDAUs,
  GetTemplateAverageBuildTime from querier.go to system.go
  and removes auth checks
- dbauthz: remove AsSystem(), add individual roles for
  autostart, provisionerd, add restricted system role for 
  everything else

coderd/httpmw/hsts_test.go

@@ -96,7 +96,7 @@ func TestHSTS(t *testing.T) {
 			req := httptest.NewRequest("GET", "/", nil)
 			res := httptest.NewRecorder()
 			got.ServeHTTP(res, req)
-			
+
 			require.Equal(t, tt.expectHeader, res.Header().Get("Strict-Transport-Security"), "expected header value")
 		})
 	}