feat(cards): add card counters

[miqmago]

• Resolves: Add "cards count" for each Kanban list #3201
• Target version: main

Summary

Add card counters to each stack

TODO

• Add card counters to sidebar: would require to change server response to make counting on server side
• Add card counters to all boards view (same as before

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Documentation (manuals or wiki) has been updated or is not required

[github-actions]

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