New FlexLayout for improved content layouting

[manuelmeister]

This pull request introduces an enhanced FlexLayout with minimized configurability for better automatic positioning of aside elements in constrained spaces.

The ColumnLayout has also been updated to ensure accurate border rendering in conjunction with the new fluid layout design.

Note

The black borders around the layout nodes are still a work in progress. Feedback is particularly sought on the layout mechanism and its overall functionality, rather than visual aesthetics or code linting.

[github-actions]

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[carlobeltrame]

Haven't tried or reviewed yet. But flexbox is not a term which our users will understand, and given that the users have less control, it will feel less flexible to themthan the column layout. How about renaming it to intelligent layout or magic layout?

[manuelmeister]

Okay for me, but I tought less about actual flexbox and more about flexible as in it adapts based on the width.

In the future it could be possible to have a single flexible column where the items just wrap, or a triple column, and so on…
That's why i called it FlexLayout in the Backend and "Automatic Layout" in the frontend.

Currently it was just easier to implement two columns only, as this has the most basic functionality.

[manuelmeister]

Core Meeting Decision

Split PR into own subparts

• Separate column improvements Optimize ColumnLayout #3522
• Create papersize Implement paper and widescreen display size for activity #4026
• Create flexible layout ContentNode: Create new responsive layout #4071

[manuelmeister]

Superceded by #3522, #4026 & #4071