markup/goldmark: Add attributes support for blocks (tables etc.)

E.g.:

```
> foo
> bar
{.myclass}
```

There are some current limitations: For tables you can currently only apply it to the full table, and for lists the ul/ol-nodes only, e.g.:

```
* Fruit
  * Apple
  * Orange
  * Banana
  {.fruits}
* Dairy
  * Milk
  * Cheese
  {.dairies}
{.list}
```

Fixes #7548

markup/goldmark/convert.go

@@ -21,6 +21,8 @@ import (
 	"path/filepath"
 	"runtime/debug"
 
+	"github.com/gohugoio/hugo/markup/goldmark/internal/extensions/attributes"
+
 	"github.com/gohugoio/hugo/identity"
 
 	"github.com/pkg/errors"
@@ -137,10 +139,14 @@ func newMarkdown(pcfg converter.ProviderConfig) goldmark.Markdown {
 		parserOptions = append(parserOptions, parser.WithAutoHeadingID())
 	}
 
-	if cfg.Parser.Attribute {
+	if cfg.Parser.Attribute.Title {
 		parserOptions = append(parserOptions, parser.WithAttribute())
 	}
 
+	if cfg.Parser.Attribute.Block {
+		extensions = append(extensions, attributes.New())
+	}
+
 	md := goldmark.New(
 		goldmark.WithExtensions(
 			extensions...,