Consider restoring `Interface::is_com_interface`

[tim-weis]

Suggestion

#4230 introduced several useful simplifications. One of them, I feel, went a bit over the edge, namely:

Inline trivial wrapper — Interface::is_com_interface was a single-line wrapper around cursor.has_pure_virtual_methods(); both call-sites are inlined and the method removed.

The update kept the semantics unchanged, but dropped two pieces of information along the way:

• the function name
• the doc comment explaining that it implements a heuristic and what that heuristic (currently) is

This isn't anything major, though, as a human, I found the previous version with a function easier to comprehend. I can draft a PR that restores the function (and call sites) if you share the sentiment.

[kennykerr]

I don't know - I generally prefer brevity. If the function actually did more to ensure the type is an interface then it might make sense but as it stands its clearly not. This is related to #4249 - I imagine if this were fixed it could make sense to reintroduce a function like is_com_interface.