fix(mtp): send run request test selection as tests not testCases - #3755

Cannot convert null literal to non-nullable reference type.

Possible null reference argument for parameter 'first' in 'IEnumerable<string> Enumerable.Except<string>(IEnumerable<string> first, IEnumerable<string> second)'.

Cannot convert null literal to non-nullable reference type.

Non-nullable property 'Description' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'DisplayName' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'ReplacementNode' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'OriginalNode' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'Details' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Nullability of type of parameter 'obj' doesn't match overridden member (possibly because of nullability attributes).