[#2042] Fix margins for Userfeed and Home

[jiromaykin]

issue: https://taiga.maykinmedia.nl/project/open-inwoner/task/2042

This is a first start to begin transforming the main grid in such a way that 'components no longer have outside margins around themselves - the parent grid should determine the spacing between components, not the components themselves - see also the temporary margin-top fix here that was the original reason for this PR.

This PR also enables spacing between plugins on the Home page by wrapping them with a Section - so you can move around any of the plug-ins in any order without having to constantly update any combination of margins between cards & heading, between cards and questionnaires, between userfeed and video, etc, etc.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.91%. Comparing base (5e6f11e) to head (c6dda1a).

❗ Current head c6dda1a differs from pull request most recent head 02de82f. Consider uploading reports for the commit 02de82f to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1048   +/-   ##
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  Coverage    94.91%   94.91%           
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  Files          882      882           
  Lines        30792    30792           
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  Hits         29227    29227           
  Misses        1565     1565           

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[pi-sigma]

Looking good. I do wonder about the styling convention. h1 elements are now styled as utrecht-heading-1 but h2 elementss continue to receive class="h2"? Is that an oversight or intentional? Just so I know which convention to follow when I write this myself...

[jiromaykin]

Looking good. I do wonder about the styling convention. h1 elements are now styled as utrecht-heading-1 but h2 elementss continue to receive class="h2"? Is that an oversight or intentional? Just so I know which convention to follow when I write this myself...

Currently this was intentional - I need another design-token sprint in order to create more values from NL Design System classes that we can use. Also: in Open-Inwoner we have a bit of a complicated H2 element that uses flexbox in order to get 'indicator' icons and sometimes the H2 wraps itself around a button so H2 in particular is more complicated to completely rework; the other Headings will be much more straightforward.