Add HtmlAgilityPack references to VS templates

[Jand42]

Templates work as they are as, but still I don't exactly what is including HtmlAgilityPack.dll in bin folder as it is not referenced. It would be better to explicitly reference HtmlAgilityPack from NuGet.

[granicz]

Well, UI is for sure - but also see here: https://github.com/search?q=org%3Adotnet-websharper+htmlagilitypack&type=code

[granicz]

Investigate and resolve if all is OK.