clipping paths are antialiased even if export is set to no antialiasing
#### Summary:
When exporting a file with a clipping path or a mask to PNG, the result is antialiased even if the export option is set not to antialias
#### Steps to reproduce:
- open Inkscape
- use a object-clip-set with a non-rectangle shape
- export to PNG with no antialiasing
#### What happened?
file looks antialiased
#### What should have happened?
file looks blocky
Sample attachments:
Example file :
```xml
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:cc="http://creativecommons.org/ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns="http://www.w3.org/2000/svg"
xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
width="1000"
height="1000"
viewBox="0 0 264.58333 264.58334"
version="1.1"
id="svg8">
<defs
id="defs2">
<clipPath
clipPathUnits="userSpaceOnUse"
id="clipPath841">
<path
id="path843"
style="fill:#00ffff;stroke:none;stroke-width:7.07128;stroke-linecap:round;stroke-linejoin:round;paint-order:stroke fill markers"
d="M 264.58333,132.29167 A 132.29167,132.29167 0 0 1 132.29167,264.58333 132.29167,132.29167 0 0 1 3.3333333e-6,132.29167 132.29167,132.29167 0 0 1 132.29167,0 132.29167,132.29167 0 0 1 264.58333,132.29167 Z" />
</clipPath>
</defs>
<g
inkscape:label="Layer 1"
inkscape:groupmode="layer"
id="layer1">
<path
id="rect12"
style="fill:#ff0000;stroke:none;stroke-width:1.05833;stroke-linecap:round;stroke-linejoin:round;paint-order:stroke fill markers"
d="M 0,0 H 264.58333 L 0,264.58333 Z"
sodipodi:nodetypes="cccc"
clip-path="url(#clipPath841)" />
</g>
</svg>
```
#### Version Info:
```
- Inkscape Version: 1.0+
- Operating System: any
```
Remarks to whoever wants to try to tackle this : in `src/diplay/drawing-item.cpp` please take the lines 711-726 and make it a static function taking arguments `dc` and `_antialias`, so that you can call it from other places (say, from the `::clip` method, if that has chances to work)
issue