Render per-repo pull request template

[AetherUnbound]

Fixes

Fixes #1470 by @AetherUnbound

Description

This PR allows the PULL_REQUEST_TEMPLATE.md file to be rendered with repo-specific additions. I took inspiration from the existing examples in order to set this one up, but @dhruvkb please let me know if there's a better way to do this! I believe there was also a desire to add some additional checks to the frontend repo's template, that could be done in this PR as well.

In order to make things less cluttered, I also moved all the templates into a templates folder at the top level, and changed the logic within the .pre-commit-config.local.yaml.jinja file to iterate over a list.

Testing Instructions

1. just lint should produce no changes
2. Running just render templates/PULL_REQUEST_TEMPLATE.catalog.md.jinja .github/PULL_REQUEST_TEMPLATE.md should produce a change to the pull request template with the additional rendered content.

Checklist

• My pull request has a descriptive title (not a vague title like
  Update index.md).
• My pull request targets the default branch of the repository (main) or
  a parent feature branch.
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added or updated tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no visible
  errors.

Developer Certificate of Origin

Developer Certificate of Origin

Developer Certificate of Origin
Version 1.1

Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
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Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.

[dhruvkb]

Looks good to me!

[dhruvkb]

This is an amazing use of Jinja, I love it!

[AetherUnbound]

I wish we could make even the list itself dynamic so we didn't have to update it, but alas that seems more challenging than it's worth 😅

[zackkrida]

LGTM! Nice approach. And will be easily adjustable if we decide we need new blocks beyond the additional_sections and additional_checks blocks created here.