Allow passing Matrix3x2 to DrawTextProcessor

[antonfirsov]

Follow-up on the discussion #124.

We should enable using an arbitrary Matrix3x2 transform as a parameter within DrawTextProcessor.

The easiest implementation seems to be to pass it to PathBuilder here:

ImageSharp.Drawing/src/ImageSharp.Drawing/Processing/Processors/Text/DrawTextProcessor{TPixel}.cs

Line 223 in e09fe9b

this.builder = new PathBuilder();

Open questions

Before implementing, we need to figure out how does the transform interfere with DrawTextProcessor.Location and ultimately RenderOptions.Origin. Ideally, I would replace DrawTextProcessor.Location with DrawTextProcessor.Transform entirely, but there might be things I'm missing.

@tocsoft any thoughts?