Automate "needs decision"

[brettcannon]

If an issue has the "needs decision" label added, then:

1. Add a canned response about how to upvote the issue
2. Have that canned comment link directly to the opening comment to help make clear that people should 👍 on that issue and not the canned response
3. Add a seeding 👍 on the opening comment

[brettcannon]

The current canned response

Thank you for the suggestion! We have marked this issue as "needs decision" to make sure we have a conversation about your idea. We plan to leave this feature request open for at least a month to see how many 👍 votes the opening comment gets to help us make our decision.

[brettcannon]

@nnja the issue we were talking about.