Right-Panel is overflowing during form-edit

### Right-Panel is overflowing during form-edit.

If the height of the form-body is too large, the right-panel starts to overflow and adds unused space at the bottom of the container. The issue only appears if the form contains boolean fields.


### Browser
Firefox 83.0 (64-bit)
The problem seems not to appear with the chrome browser.

### Cause

The problem is produced by the styling of gtx-checkbox.
```
gtx-checkbox [type="checkbox"]:not(:checked), gtx-checkbox [type="checkbox"]:checked {
position: absolute;
left: -9999px;
opacity: 0;
}
```

The editor-body is static positioned, thus the checkbox-element is anchored outside of the editor-body causing the right-panel to overflow.

A possible fix would be adding `position: relative` to the `mesh-boolean-field` to provide an anchor inside the editor-body.

Start by locating the gtx-checkbox styling and the mesh-boolean-field used by the form editor. Reproduce the issue in Firefox with a tall form containing boolean fields, then verify that the right panel no longer overflows or leaves unused space at the bottom.

Written by the indexing model from the issue text.