Add automated review action

[cottsay]

This adds a preliminary automated reviewer for changes to this repository.

At present, only changes to rosdep are supported and there are probably a lot of rough edges, but it will still probably provide value as we continue to develop it and add additional checks.

It will be invoked when a PR is opened, but does not re-evaluate a PR until review is re-requested for github-actions[bot]. PR authors and rosdistro maintainers should both have the capability to re-request review.

(among the rough edges is documenting this behavior in the PR body)

[fujitatomoya]

This is still draft, but i believe this is really nice to support the review process with automated review comments.

I did not see the details of https://github.com/ros-infrastructure/rosdistro-reviewer, but do we already have the sample review result for the pull request?

[github-actions]

This PR hasn't been activity in 14 days. If you are still are interested in getting it merged please provide an update. Otherwise it will likely be closed by a rosdistro maintainer following our contributing policy. It's been labeled "stale" for visibility to the maintainers. If this label isn't appropriate, you can ask a maintainer to remove the label and add the 'persistent' label.

[cottsay]

Here are some demos!

A good PR: cottsay#28
A PR that needs changes: cottsay#29

[nuclearsandwich]

Yesssssssss