[TASK] Expose raw definition of backend layout model

Allows to make use of custom properties in backend layouts,
e.g. like shown below in Fluid templates:

```
<f:if condition="{column.definition.myFeature}">
  <div data-colpos="{column.columnNumber}">...</div>
</f:if>
```

Resolves: #94634
Releases: master
Change-Id: I2dc2b7324bbcabc55a8896f74c3dd79768a0b87d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70067


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>