JSON projection should support nested paths

[chripf]

When using JSON projection for nested elements the Code is quite lenghty:

return t => {
      Field1 = t.JsonData.RootElement.GetProperty("outer").GetProperty("nested1").GetProperty("nested2").GetString()
}

This would read much nicer as

return t => {
      Field1 = t.JsonData.RootElement.GetProperty("outer.nested1.nested2").GetString()
}