Make it easier to re-assign a form field to `auto` columns

[pinussilvestrus]

Is your feature request related to a problem? Please describe.

Sometimes I want my form field to align automatically with the available space inside a row. There is the auto columns option for this, which is used once no columns are defined.

However, after setting a fixed value for columns, there is no way to reset to auto columns on the canvas, only via the properties panel. This can be pretty cumbersome, especially when using the resize feature.

Describe the solution you'd like

Make it easier to go back to the auto columns.

One idea arrives via Slack to implicitly set the auto behavior for form fields with 16 columns. The disadvantage here would be more magic under the hood. Additionally, there still needs to be a way for multiple form fields inside a row.

Describe alternatives you've considered

Keep everything as is, no magic.

Additional context