feat(generic): list all generic models on overview page

[b1rger]

This commit introduces the templatetag genericmodel_content_types
which lists all content types of models that inherit from
apis_core.generic.abc.GenericModel. This templatetag is then used
in the overview template to create an overview of all those
contenttypes and not only apis_ontology and collections as it was
hardcoded beofre.

Closes: #912

[koeaw]

So, what I find weird about this is that the history models appear under separate, second sections for the apps they belong to, further down the page.

I think it would make more sense if they appeared in closer proximity, and under the same section headline. Ideas: the sections could be split in half, with the left side containing the main models, the right side the histories. Or, models and histories could come in pairs? First button links to main models, second to that model's history.

I'm trying to think how I'd most likely look up/look for histories, and I think in my head I'd go by model name first, history second, so the idea of button pairs seems like it would take the least amount of time searching for the right button to click on.

[koeaw]

Hmm, also, I see myself opening both the model and its history in parallel , e.g. to check I'm looking at the right object if there are several similar/same-ish named ones (which is the case in Frischmuth), for which the two buttons next to each other would also help.

[b1rger]

So, what I find weird about this is that the history models appear under separate, second sections for the apps they belong to, further down the page.

Can you create a screenshot? The PR only splits the models by the app they belong to and the versions are part of the same app, so they should be part of the same section

[koeaw]

This is what it looks like on my end:

[b1rger]

This is what it looks like on my end:

Hm, interesting, thats not how it should look

[b1rger]

So, what I find weird about this is that the history models appear under separate, second sections for the apps they belong to, further down the page.

Thats fixed now

[koeaw]

Yep, looks fine for me now!