Add `view-file` macro

Example:
```xml
<ac:structured-macro ac:name="view-file" ac:schema-version="1" ac:macro-id="...">
  <ac:parameter ac:name="name">
    <ri:attachment ri:filename="..." ri:version-at-save="1"/>
  </ac:parameter>
  <ac:parameter ac:name="height">250</ac:parameter>
</ac:structured-macro>
```

Parameters: ?