Fix InvalidCastException in ConvertForToForEach with tuples

[deepakrathore33]

Fixes 81530

Problem

VS crashes with InvalidCastException when "Convert to foreach" refactoring analyzes
a for loop where the iteration variable is used inside a tuple:

for (int i = 0; i < array.Length; i++)
{
    var tuple = (array[i], i);  // crash here
}

Cause

TupleExpressionSyntax contains ArgumentSyntax children but is NOT a BaseArgumentListSyntax
The code assumed argument's parent is always a valid argument list.

Fix

Check if it's a valid element access or invocation BEFORE calling GetArgumentsOfArgumentList

Testing

Added TestNotWithIterationVariableInTupleExpression

[CyrusNajmabadi]

Thanks!

[deepakrathore33]

Fixes: #81608