Customizable "Open with" applications for repository clone (#29320)

Users could customize the "clone" menu with their own application URLs on the admin panel.

Replace #22378
Close #21121
Close #22149

modules/context/context.go

@@ -192,6 +192,7 @@ func Contexter() func(next http.Handler) http.Handler {
 			httpcache.SetCacheControlInHeader(ctx.Resp.Header(), 0, "no-transform")
 			ctx.Resp.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
 
+			ctx.Data["SystemConfig"] = setting.Config()
 			ctx.Data["CsrfToken"] = ctx.Csrf.GetToken()
 			ctx.Data["CsrfTokenHtml"] = template.HTML(`<input type="hidden" name="_csrf" value="` + ctx.Data["CsrfToken"].(string) + `">`)