Add TagHelperSample.Web

Add Tag Helper sample, #1242
It's not different than class, rows, value.  I was just looking at all your uses of `validation-message` and none of them provided any non-taghelper specific attributes.

I think you covered all the helpers currently planned, I'm just saying if there are any helpers in this project that don't showcase that they allow extra attributes to flow through to just add a class, or a style attribute to them.