ADD: Context to Renderer

[grishat]

Added MarkdownParserContext to Renderer.

I wrote my own LinkExtension render TryLinkInlineRenderer, and need context access from HtmlRenderer, that available only in parser.

    public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
    {
        if (renderer is HtmlRenderer htmlRenderer)
        {
            var inlineRenderer = htmlRenderer.ObjectRenderers.FindExact<LinkInlineRenderer>();
            if (inlineRenderer != null)
            {
                inlineRenderer.TryWriters.Remove(TryLinkInlineRenderer);
                inlineRenderer.TryWriters.Add(TryLinkInlineRenderer);
            }
        }
    }

    private bool TryLinkInlineRenderer(HtmlRenderer renderer, LinkInline link)
    {
        ...
       var propValue = (string?)renderer.Context?.Properties["PropName"];
        ...
    }

I think the context should be available both in the parser and in the render. This required minimal changes.
What do you think?

[MihaZupan]

Seems reasonable to me to extend the context to rendering

[MihaZupan]

Suggested change

	using var rentedRenderer = pipeline.RentHtmlRenderer(null, context);
	using var rentedRenderer = pipeline.RentHtmlRenderer(writer: null, context);

[MihaZupan]

The MarkdownParserContext may be different for each parsing operation and shouldn't be cached between uses of the renderer.

Instead of storing the context on HtmlRendererCache, set it after renting it like we do with the writer and then null it out in Reset.

[grishat]

I get you, it turned out to be a little more complicated than I thought.
I found walkaround for me. I think I need to close this PR. I can't run the tests either on my local machine.