experiment: add form-layout base styles and visual tests

[anezthes]

New FormLayout base style

Supported custom properties

Property	Description
--vaadin-form-layout-label-spacing	Spacing between form item labels and fields.
--vaadin-form-layout-label-width	Default width for labels when placed beside fields.
--vaadin-form-layout-column-spacing	Horizontal spacing between columns in the form layout.
--vaadin-form-layout-row-spacing	Vertical spacing between rows in the form layout.
--vaadin-form-item-label-color	Color of the form item labels.
--vaadin-form-item-label-font-size	Font size of the form item labels.
--vaadin-form-item-label-font-weight	Font weight of the form item labels.
--vaadin-form-item-label-line-height	Line height of the form item labels.
--vaadin-form-item-label-width	Width of individual form item labels.

Changes from 'core'

In auto-responsive mode, vaadin-form-item has its margin set to 0.

[jouni]

Okay IMO. I’m not 100% sure about the need for both --vaadin-form-layout-label-width and --vaadin-form-item-label-width, but since those are pre-existing properties, I think it’s fine to keep them. No other harm than perhaps documenting both.

Should add visual tests for base styles, though.

[web-padawan]

I'll look into adding visual tests and then will rebase the PR for CRUD on top of this one just in case.

[web-padawan]

Regarding --vaadin-form-item-label-width - it's deprecated in 24.7, maybe we could remove item properties.

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud