[#1109] Feature/update plan list view

[vaszig]

• Status column shows 'Open' (open plan) or 'Afgerond' (expired plan)
• Openstaande acties shows the number of 'open' actions (if status is 'open' or 'approval') with the proper message ('Actie vereist')

[codecov-commenter]

Codecov Report

Merging #462 (a0f80bd) into develop (73137fd) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #462      +/-   ##
===========================================
+ Coverage    96.43%   96.46%   +0.02%     
===========================================
  Files          495      505      +10     
  Lines        17664    18255     +591     
===========================================
+ Hits         17034    17609     +575     
- Misses         630      646      +16     

Impacted Files	Coverage Δ
src/open_inwoner/plans/models.py	98.50% <100.00%> (+0.23%)	⬆️
src/open_inwoner/plans/tests/test_views.py	100.00% <100.00%> (ø)
src/open_inwoner/plans/views.py	97.52% <100.00%> (+0.24%)	⬆️
src/open_inwoner/utils/validators.py	84.61% <0.00%> (-15.39%)	⬇️
src/open_inwoner/openzaak/models.py	97.82% <0.00%> (-2.18%)	⬇️
src/open_inwoner/openzaak/tests/factories.py	98.57% <0.00%> (-1.43%)	⬇️
.../open_inwoner/components/templatetags/file_tags.py	86.11% <0.00%> (-0.38%)	⬇️
src/open_inwoner/openzaak/admin.py	90.35% <0.00%> (-0.35%)	⬇️
src/open_inwoner/openzaak/notifications.py	95.12% <0.00%> (-0.34%)	⬇️
src/open_inwoner/openzaak/documents.py	94.59% <0.00%> (-0.08%)	⬇️
... and 26 more

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[vaszig]

Discussed with Alex and added only one small fix concerning pagination to this PR because it's not yet merged in.