Pass .RenderShortcodes' Page to render hooks as .PageInner

The main use case for this is to resolve links and resources (e.g. images) relative to the included `Page`.

A typical `include` would similar to this:

```handlebars
{{ with site.GetPage (.Get 0) }}
  {{ .RenderShortcodes }}
{{ end }}
```

And when used in a Markdown file:

```markdown
{{% include "/posts/p1" %}}
```

Any render hook triggered while rendering `/posts/p1` will get `/posts/p1` when calling `.PageInner`.

Note that

* This is only relevant for shortcodes included with `{{%` that calls `.RenderShortcodes`.
* `.PageInner` is available in all render hooks that, before this commit, received `.Page`.
* `.PageInner` will fall back to the value of `.Page` if not relevant and will always have a value.

Fixes #12356

hugolib/content_map_page.go

@@ -1603,7 +1603,7 @@ func (sa *sitePagesAssembler) assembleResources() error {
 			targetPaths := ps.targetPaths()
 			baseTarget := targetPaths.SubResourceBaseTarget
 			duplicateResourceFiles := true
-			if ps.s.ContentSpec.Converters.IsGoldmark(ps.m.pageConfig.Markup) {
+			if ps.m.pageConfig.IsGoldmark {
 				duplicateResourceFiles = ps.s.ContentSpec.Converters.GetMarkupConfig().Goldmark.DuplicateResourceFiles
 			}