(Enhancement) Ignore particular lines

Could you add an option to have this VSCode extension ignore particular lines? For example, any line that includes "`/* csstree-ignore-line */`".

I have some code in my CSS for older browsers (e.g. `-webkit-margin-before:`, `-webkit-margin-after:`, `width: -webkit-fill-available`, `width: -moz-available`, and `width: fill-available`), which are reported as errors, and I'd rather have an empty "Problems" window in VSCode. Giving me a way to have your extension not report those lines as errors would really be appreciated.

Thank you, and thank you for the VSCode extension. :smiley: