GraphicFillPadding needed to add space around Fill repeated pattern

[ger-benjamin]

Feature Request

Is your feature request related to a problem? Please describe.

Using geostyler-lyrx-parser, I can read polygon with FillGraphic pattern. But I can not translate the padding around repeated symbols. (The offset didn't help)
The result is this one:

Describe the solution you'd like
I would like a solution to have space around PointSymbolizer fill marker in polygon. I propose to add a GraphicFillPadding?: expression<number>[] next to the GraphicFill poperty in on the FillSymbolizer: https://geostyler.github.io/geostyler-style/docs/main/interfaces/FillSymbolizer.html#graphicFill

The result could be something like:

Describe alternatives you've considered
Otherwise, it would be possible to add a adding in the PointSymbol itself, but I think it doesn't make sens in other context than the GraphicFill/FillSymbolizer.

Additional context
In my use case, the GraphicFillPadding would be translated as VendorOption "graphic-margin" in the geostyler-sld-parser.
See also the related geostyler-lyrx-parser issue: geostyler/geostyler-lyrx-parser#64