Implementing OpenApi 3 specs (converted from Swagger 2) (#53243)

* Adding OpenApi target to makefile, to covert swagger spec into OpenAPI 3
* Adding endpoint to server swaggerui with new openapi3 specs
* Passing output file as parameter for OpenApi3 specs
* Implement workaround for missing host and prefix domain

pkg/api/api.go

@@ -187,6 +187,7 @@ func (hs *HTTPServer) registerRoutes() {
 
 	if hs.Features.IsEnabled(featuremgmt.FlagSwaggerUi) {
 		r.Get("/swagger-ui", swaggerUI)
+		r.Get("/openapi3", openapi3)
 	}
 
 	// authed api

pkg/api/openapi3.go

@@ -0,0 +1,11 @@
+package api
+
+import (
+	"net/http"
+
+	"github.com/grafana/grafana/pkg/models"
+)
+
+func openapi3(c *models.ReqContext) {
+	c.HTML(http.StatusOK, "openapi3", nil)
+}