chore: Add curated democontent

[mrbazzan]

JSON data from this page

[mrbazzan]

@fsbraun
On data import from blog.json, the Picture/Image plugin in the TextPlugin
does not render (It appears in the structure board but not in the actual plugin).

PS: The one that is encoded as <cms-plugin alt=\"Picture / Image - Image (274)\" title=\"Picture / Image - Image (274)\" id=\"274\"></cms-plugin>

[fsbraun]

@mrbazzan Interesting! Indeed, for text plugins the id of the child plugin also has to be changed within the text'S body field (i.e., the 274 be replaced by the actual pk of the child plugin everywhere inside <cms-plugin></cms-plugin>. Would that need to be done here or in djangocms-transfer?

Could be a task for regex.

[mrbazzan]

@fsbraun
That would mean finding the new pk; I'd like to think that's something djangocms-transfer should do?

Could this be done with the import and export processing setting in djangocms-transfer?

[fsbraun]

@mrbazzan Probably this needs to be done at the import - where it is already done for other pk references, e.g., plugin parents.

[mrbazzan]

where it is already done for other pk references, e.g., plugin parents.

@fsbraun On further search, I found djangocms-transfer require plugins that serialize references
to other plugin in its data needs to define a do_post_copy method that does the conversion.

TextPlugin already defines the do_post_copy method but it doesn't add the attribute hook, _has_do_post_copy which
allows djangocms-transfer to use the method. Instead of using the hook (which is undocumented I think), we could check if each plugin class has "do_post_copy" and call it?

[fsbraun]

@mrbazzan Can this be merged?