[dotnet] Use ChangeType method to convert any object to boolean in WebElement propoerties

[nvborisenko]

This approach brings us a possibility to track what exactly we try to convert.

Description

var a = (object)"true"; var b = (bool)a;

It always throws InvalidCastException.

There is safer method:

var a = (object)"true"; var b = (bool)Convert.ChageType(a, typeof(bool));

Even if input is not formatted well to be boolean, then we will get more clear exception:

System.FormatException: String 'false 66' was not recognized as a valid Boolean. 

where false 66 is incorrect input.

Motivation and Context

Just to get more clear understanding what is going wrong, and highlight a value returned from server side.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[diemol]

Thank you, @nvborisenko!