Refactor markup render system (#32589)

This PR mainly moves some code and introduces `RenderContext.WithXxx`
functions

routers/web/feed/convert.go

@@ -51,16 +51,14 @@ func toReleaseLink(ctx *context.Context, act *activities_model.Action) string {
 // renderMarkdown creates a minimal markdown render context from an action.
 // If rendering fails, the original markdown text is returned
 func renderMarkdown(ctx *context.Context, act *activities_model.Action, content string) template.HTML {
-	markdownCtx := &markup.RenderContext{
-		Ctx: ctx,
-		Links: markup.Links{
+	markdownCtx := markup.NewRenderContext(ctx).
+		WithLinks(markup.Links{
 			Base: act.GetRepoLink(ctx),
-		},
-		Metas: map[string]string{ // FIXME: not right here, it should use issue to compose the metas
+		}).
+		WithMetas(map[string]string{ // FIXME: not right here, it should use issue to compose the metas
 			"user": act.GetRepoUserName(ctx),
 			"repo": act.GetRepoName(ctx),
-		},
-	}
+		})
 	markdown, err := markdown.RenderString(markdownCtx, content)
 	if err != nil {
 		return templates.SanitizeHTML(content) // old code did so: use SanitizeHTML to render in tmpl
@@ -296,14 +294,13 @@ func releasesToFeedItems(ctx *context.Context, releases []*repo_model.Release) (
 		}
 
 		link := &feeds.Link{Href: rel.HTMLURL()}
-		content, err = markdown.RenderString(&markup.RenderContext{
-			Ctx:  ctx,
-			Repo: rel.Repo,
-			Links: markup.Links{
+		content, err = markdown.RenderString(markup.NewRenderContext(ctx).
+			WithRepoFacade(rel.Repo).
+			WithLinks(markup.Links{
 				Base: rel.Repo.Link(),
-			},
-			Metas: rel.Repo.ComposeMetas(ctx),
-		}, rel.Note)
+			}).
+			WithMetas(rel.Repo.ComposeMetas(ctx)),
+			rel.Note)
 		if err != nil {
 			return nil, err
 		}