Support including port part in trusted-host

[frostming]

Closes #6886
Closes #6710

This PR proposes official support for including port part in trusted-host option, for both HTTP and HTTPS indexes. So:

--trusted-host example.com trusts all these indexes:

• http://example.com
• http://example.com:8080
• https://example.com
• https://example.com:8080

While --trusted-host example.com:8080 only trusts the indexes with port 8080 exactly:

• http://example.com:8080
• https://example.com:8080

[cjerdonek]

Thanks! A couple comments. Also, the command-line help should be updated to reflect the change.

[cjerdonek]

Thanks for the updates. Looking a lot better! Some more comments.

[cjerdonek]

Thanks for your changes. One more comment that I can see. Almost there!

[cjerdonek]

Oh, and there is still the comment from before re: updating the command-line help to say that host-port pair is also acceptable. That code is in cmdoptions.py.

[cjerdonek]

I came across another thought: what if the index URL is HTTPS and contains auth part? ...

@frostming By the way, regarding the comment quoted above, would you mind filing that as a separate issue so we don't lose track of it? It would be much appreciated..

[cjerdonek]

FYI, I made some minor formatting tweaks in preparation for merging.

[cjerdonek]

Thanks again, @frostming! 🎉

[frostming]

@cjerdonek Thanks for that, I created #6931 to track the remaining issue.