MNT: a pull request template for new frontends

[neutrinoceros]

The process of adding new frontends has a lot of steps that are not clear to (often new) contributors and easy to forget as maintainers. It would help if we had a specialised pull request template including a task list.

in particular, adding tests for new frontends is significantly more involved than regular tests because it implies storing sample data. This process ought to be better documented.

[matthewturk]

This is an awesome idea! I'd love to see if we can combine this with @chrishavlin 's skeleton of a frontend, and maybe really streamline the process.

[chrishavlin]

@matthewturk you mean https://github.com/data-exp-lab/ytcookiecutter ? i should check how that's working these days, it probably needs some updates....

and I like this idea too!

[neutrinoceros]

Another thing that I wanted to note: the checklist should include "create an 'extra' target for optional dependencies (even if you have none) in pyproject.toml"
(all current frontends were merged before this became a thing, so we won't see it in existing examples)