Support __index__ on additional code paths in Bytes/ByteArray construction

[BCSharp]

I had to tweak bytes construction a little again. Apparently, it is not only "always call __bytes__", but also "always call __index__" — except when constructing from str or int derived classes…

A similar story in bytearray.

[slozier]

Looks good to me.

A though that came to be while looking is that int.from_bytes(2, 'big') probably shouldn't work (and indeed it doesn't with CPython). Similarly, there should be no __index__ calls when going through int.from_bytes.

[BCSharp]

Any idea why test_smtpnet.SmtpTest('test_connect_starttls') fails on Azure Pipelines?

[slozier]

No idea for the smtp stuff. Looking at the log is seems like test_smtplib runs to completion in about 5 seconds, but them becomes stuck and times out after 10 minutes.