Teach `open-issue.js` to look whether a ticket exists for the given version already

[dscho]

In #8, a redundant ticket was opened, mainly because open-issue.js does not bother to look whether there exists a ticket for the given component update yet, unlike what the rss-to-issues Action does in our RSS feed-based workflow monitoring Git for Windows' components.

Let's teach the same trick to open-issue.js.