Initial commit for tooltip

Tooltip was made as it assumed to be. As it was expected, tooltip covers Scrollbar and user can not use the scroll with mouse until tooltip is opened. Please review code and close that pull request  https://github.com/DynamoDS/Dynamo/pull/2026 because it was made in the wrong brach. I apologize about that wrong pull request, that will not happen again.
There are a few things we can do to improve ```InputParameterTypeConverter```:

1. Since it is used for input/output parameters, name it as ```InOutParamTypeConverter```.
2. Instead of ```true```, let's check for ```inputParam``` instead (making the intention clearer).
3. Update ```TooltipWindow.xaml``` to use ```inputParam```, and then format the entire XAML file.
4. Add documentation for ```InOutParamTypeConverter``` as below:

```cs
/// This converter is used to format the display string for both input and output 
/// parameters on the "TooltipWindow.xaml". If "parameter" here is "inputParam", 
/// then this converter is invoked by input parameter related binding. A colon 
/// character will be prefixed to the parameter type (e.g. "value : double") only 
/// for input parameter (since an output of a function does not have a name). Also,
/// the colon will only appended when there is actually an input parameter (for 
/// cases without input parameter, only "none" string will be displayed so there is 
/// no point in prefixing a colon character (e.g. we don't want ": none").
```