Fix C# template

[vkudley]

Fixes for C# template:

• Boolean --> bool
• String --> string
• Xpath -- XPath
• Properties instead of methods
• Expression body instead of methods
• Underscore for _driver to stylize as private field
• Shorter comment/name for groups It passed limited testing using private build

[danhumphrey]

Apologies for the delay, but thank you for the contribution - I will merge this shortly!