API: Extract OpenAPI specification from source code using go-swagger (#40528) (#45061)

* API: Using go-swagger for extracting OpenAPI specification from source code

* Merge Grafana Alerting spec

* Include enterprise endpoints (if enabled)

* Serve SwaggerUI under feature flag

* Fix building dev docker images

* Configure swaggerUI

* Add missing json tags

Co-authored-by: Ying WANG <ying.wang@grafana.com>
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>
(cherry picked from commit 35fe58de37)

pkg/api/api.go

@@ -141,6 +141,10 @@ func (hs *HTTPServer) registerRoutes() {
 	// expose plugin file system assets
 	r.Get("/public/plugins/:pluginId/*", hs.getPluginAssets)
 
+	if hs.Features.IsEnabled(featuremgmt.FlagSwaggerUi) {
+		r.Get("/swagger-ui", swaggerUI)
+	}
+
 	// authed api
 	r.Group("/api", func(apiRoute routing.RouteRegister) {
 		// user (signed in)