Added methods to drawing thin poly-lines

[Chaosus]

This is one of the ways to fix #44332 - I've added add_thin_polyline to RenderServer and draw_thin_polyline, draw_thin_polyline_colors, draw_thin_arc to CanvasItem. Instead PRIMITIVE_TRIANGLE_STRIP it used PRIMITIVE_LINE and does not have thickness and antialiasing parameters.

Also, the line with width < 1.0 is already draw incorrectly - for example with width = 0.1:

so I've added a limiter to canvas_item_add_polyline to prevent this.

[briansemrau]

I'm uncertain whether limiting width to a minimum of 1.0 is the way to go. If someone prefers to use the canvas zoomed in, they might want to draw thinner lines than that. And I would expect the line at width=1 to disappear anyway if you zoomed out, right?

[Chaosus]

I don't think that disappearing and invalid looking lines should be expected behavior - if you really need them to disappear you could do it programmatically by detecting the required zoom level.

[briansemrau]

Yeah I agree, I just don't think there's an easy way to avoid that because canvas scaling will always be able to scale (non-hairline) geometry small enough to disappear.

[Chaosus]

There always been some limitations the goal is to keep balance like anywhere in the engine.

[Chaosus]

And I would expect the line at width=1 to disappear anyway if you zoomed out, right?

Yes, and I think it's not fixable (or at least I don't know how), but at least you will have a thin line which is a different kind of geometry that always preserved its form.

[Chaosus]

Closed in favor of #44361 (I think it's more compact and relevant)