Feature/istwcms 5905 ibiki section background

config/install/layout_builder_styles.group.uw_lbs_section_background_style.yml

+langcode: en
+status: true
+dependencies: {  }
+id: uw_lbs_section_background_style
+label: 'Background style'
+multiselect: single
+form_type: checkboxes
+required: false
+weight: 0