Rethink of Boolean attributes defaults and editing

• logic for setting attribute defaults is moved from native into _hookMetadataTransformation.js:
  • for 'Text', 'Document', 'Many' attributes force allowSort = false
  • for Boolean attributes force defaultValue = '0'.
• metadata for attributes of type Boolean: removed allowNull: false and defaultValue - not needed anymore
• u-auto-filed for attributes of type Boolean internally use u-checkbox instead of el-checkbox. It's recommended do not force internal component for Booleans using force-cmp="el-switch" - u-checkbox is good enough
• u-checkbox and u-radio size increased to 20px (to be the same height as el-switch); Size is defined in --u-checkbox-dim css variable