Distribute forms over multiple views

[henhuy]

In contrary to former setup of forms, we want to distribute them over multiple views in order to lower information / overhead per page for the user.
But this means, that we have to "remember" the user input over multiple pages.
This is done by implementing a django session (see https://docs.djangoproject.com/en/5.0/topics/http/sessions) which keeps track of former form inputs.

TODOS:

• Set up multiple views (including forms as far as they are known right now) regarding to FIGMA mockup (see RC)
• Set up django sessions as REDIS-cached session (https://docs.djangoproject.com/en/5.0/topics/http/sessions/#using-cached-sessions)
• On each view, form shall be validated in backend after post and either same page is shown with form errors or user is leaded forwards to next page
• If user "goes back", form with former user inputs shall be recreated from session entries
• Note: Eventually, HTMX is needed on some pages, so that some parts/forms of the page are rendered depending on former user inputs. This must be "remembered" when coming back to the page and recreating forms from session!