Checkbox fields with the readOnly attribute set to true are still selectable.

Steps to reproduce

1. Go to Web resources app and edit the HTML component dialog (/mtk/dialogs/components/html.yaml) with the following snippet

   form:
     tabs:
       - name: tabMain
         fields:
           - name: editHTML
             class: info.magnolia.ui.form.field.definition.CodeFieldDefinition
             language: html
             required: true
           - name: showTitle
             fieldType: checkbox
             label: Show title
             buttonLabel: Select to display title
             readOnly: true
   
   actions:
     commit:
       class: info.magnolia.ui.admincentral.dialog.action.SaveDialogActionDefinition
     cancel:
       class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition
   

2. Move to Pages App and create a new Basic Page
3. Within that Basic Page, create an HTML component
4. Check the checkbox field is still selectable

Expected results
Checkbox field is no selectable

Actual results
Checkbox field is selectable

Workaround
N/A

Development notes
N/A