Implement codecs.strict_errors

[BCSharp]

Current codecs module lacks a number of standalone error handling functions (or, to be exact, the exported symbols are not callable):

>>> import codecs
>>> [ f for f in dir(codecs) if f.endswith("errors")]
['backslashreplace_errors', 'ignore_errors', 'replace_errors', 'strict_errors', 'xmlcharrefreplace_errors']

This PR implements strict_errors as a pilot; if the approach is agreed upon, I will implement the remaining ones in a similar fashion.

I am not quite sure whether using a delegate to put into the error handlers dictionary is the right way; perhaps there is a better, more ironpythonic way of doing it. As it is now, there are some subtle differences between IronPython and CPython regarding the type:

CPython:

>>> codecs.strict_errors
<built-in function strict_errors>
>>> type(codecs.strict_errors)
<class 'builtin_function_or_method'>
>>> codecs.strict_errors()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: strict_errors() takes exactly one argument (0 given)

IronPython:

>>> codecs.strict_errors
<IronPython.Runtime.Operations.StringOps+CodecsInfo+ErrorHandler object at 0x000000000000008E [IronPython.Runtime.Operations.StringOps+CodecsInfo+ErrorHandler]>
>>> type(codecs.strict_errors)
<class 'ErrorHandler'>
>>> codecs.strict_errors()    
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Invoke() takes exactly 1 argument (0 given)

Functionality-wise, they behave the same.

[slozier]

You can wrap the method in BuiltinFunction instead of creating delegates. Something like the following:

d["strict"] = BuiltinFunction.MakeFunction("strict_errors", ReflectionUtils.GetMethodInfos(typeof(StringOps).GetMember(nameof(StrictErrors), BindingFlags.Static | BindingFlags.NonPublic)), typeof(StringOps));

Note that I'm super familiar with this part of the codebase (BuiltinFunction) so I may be misusing it (e.g. what is the proper declaringType).

[slozier]

Thanks! Will merge once CI is done.