Is your feature request related to a problem? Please describe.
The CTA button text on process cards is always "Take part" even if the process is no longer in an active phase which is misleading for the users because they click on a button and do not know what to do.

Describe the solution you'd like
Allow admins to add a custom text and link for CTA button for each steps. It can actually use the existing fields used for the steps CTA :

Describe alternatives you've considered
No

Additional context
Accepted Meta Decidim Proposal : https://meta.decidim.org/processes/roadmap/f/122/proposals/14860

We implemented this on our fork. You can test it here :
https://demo.decidim.opensourcepolitics.eu/processes

Does this issue could impact on users private data?
No