Add REP-144 check list to pr template, and split pull request template files

[ijnek]

• Adds REP-144 information and updates the DOC INDEX TEMPLATE
• Since the PR template becomes rather large and readability is reduced, I have also split the pull request templates into mupltiple templates which can be selected from the root pr template.
• Improvements to language and formatting to increase readability of templates.

Supercedes #39987.

[mjcarroll]

Is the PULL_REQUEST_TEMPLATE feature new? I believe that we had tried this in the past without success, you had to put it all in a single markdown file

[ijnek]

As far as I can tell, this feature has been available for a few years. One caveat is that GitHub lacks a user-friendly interface for selecting templates, unlike GitHub issue templates (eg. ros2-gbp's issue template selection).

Without a user-friendly interface, to access the other templates, one needs to utilize a query string in the URL (e.g., ?template=rosdep_rule_template.md). To circumvent this lack of interface, the root PR template is designed to include links to the other specialized PR templates.

Here's a screenshot of the root PR:

[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.

[ijnek]

Please remove the 'stale' label, this is waiting for review

[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.

[nuclearsandwich]

I'm in favor of this change.

I hatelove the "hack" of using the default pull request template to try and provide the user interface that GitHub won't.

This adds additional "steps" to the contribution process for ros/rosdistro but makes the pull request templates more legible. I am not a product manager so I don't know what conventional wisdom suggests this would do to our "funnel" for contributors. Before I approve and merge this, I want to bring it to a ROS 2 meeting.

[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.

[nuclearsandwich]

Before I approve and merge this, I want to bring it to a ROS 2 meeting.

I haven't done this yet. It slipped my mind for the last ROS 2 meeting I attended. I've put it on the prospective agenda for the next ROS 2 meeting.

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In the intervening weeks I realized that a more radical alternative would be to separate the official rosdep sources into their own repository, thus focusing the pull request guidelines and template on rosdistro operations, which may reduce the need to work around things in this manner. It seems like the gh CLI allows specifying a template but only from local files, not starting a browser tab with a selected PR template.