Derived exceptions not caught by C#

For example:

class Test(SystemExit): pass

raise Test

does not terminate the process. The C# code expects a SystemExitException but the exception ends up being of type Exception.

Also, an IndexError (which becomes an IndexOutOfRangeException) would not be caught by LookupException handler in C# even though LookupError is a base of IndexError. For example:

try {
    PythonCalls.Call(context, somethingthatthrowsindexerror);
} catch (LookupException e) {
    // do stuff
}

would not catch the exception.

This came up in https://github.com/IronLanguages/ironpython3/pull/1011.

Start with the exception conversion around PythonCalls.Call and the C# SystemExitException and LookupException handlers; no source file or test is named in the issue. Reproduce the provided derived SystemExit and IndexError examples, then verify that the corresponding C# handlers catch them according to the Python inheritance hierarchy.