Alerting: Cleanup and move legacy to a legacy file (#32803)

* Alerting: Cleanup and move legacy to a legacy file

A quick cleanup of the ngalert/api directory, optimising for an easy
removal of what is will be considered legacy at some point. A quick
summary of what's done is:

- Add a prefix `generated` prefix to files that are auto-generated by
  our swagger definitions.
- Create a legacy file to place all the legacy API routes implementation
  and helpers. Deleting files that where no longer needed after this
move.
- Rename the `lotex` file to `lotex_ruler`
- Adding a couple of comments here and there.

With this, I hope to organise our code in this directory a bit better
given there's a lot going on.

pkg/services/ngalert/api/generated_base_api_prometheus.go

@@ -0,0 +1,26 @@
+/*Package api contains base API implementation of unified alerting
+ *
+ *Generated by: Swagger Codegen (https://github.com/swagger-api/swagger-codegen.git)
+ *
+ *Do not manually edit these files, please find ngalert/api/swagger-codegen/ for commands on how to generate them.
+ */
+package api
+
+import (
+	"github.com/grafana/grafana/pkg/api/response"
+	"github.com/grafana/grafana/pkg/api/routing"
+	"github.com/grafana/grafana/pkg/middleware"
+	"github.com/grafana/grafana/pkg/models"
+)
+
+type PrometheusApiService interface {
+	RouteGetAlertStatuses(*models.ReqContext) response.Response
+	RouteGetRuleStatuses(*models.ReqContext) response.Response
+}
+
+func (api *API) RegisterPrometheusApiEndpoints(srv PrometheusApiService) {
+	api.RouteRegister.Group("", func(group routing.RouteRegister) {
+		group.Get(toMacaronPath("/api/prometheus/{Recipient}/api/v1/alerts"), routing.Wrap(srv.RouteGetAlertStatuses))
+		group.Get(toMacaronPath("/api/prometheus/{Recipient}/api/v1/rules"), routing.Wrap(srv.RouteGetRuleStatuses))
+	}, middleware.ReqSignedIn)
+}