chore: update the PR template

[xmfcx]

Description

Old PR pipeline:

• Click on the preview button (Unintuitive)
• Select a PR template
• There are many checkboxes (nobody uses them and things get merged anyways)

Old method:

2024-06-24.16-14-10.mp4

New PR pipeline:

• Template comes right away, has the best of both templates in a single simple package.
  • Multi-line comments are color coded, easy to remove.
• Checkboxes are removed and offloaded to a CI action to comment automatically on the PR.
• Verbose/obvious comments are removed, it is very clean now.
• Test new template using this link
• Renamed the PULL_REQUEST_TEMPLATE.md to pull_request_template.md following Github's Creating a pull request template for your repository guidelines

Tests performed

• https://github.com/xmfcx/test_temp/compare/main...xmfcx-patch-2?quick_pull=1
• chore: update the PR template #7667 (comment)

Effects on system behavior

Not applicable.

Interface changes

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[github-actions]

Thank you for contributing to the Autoware project!

🚧 If your pull request is in progress, switch it to draft mode.

Please ensure:

• You've checked our contribution guidelines.
• Your PR follows our pull request guidelines.
• All required CI checks pass before marking the PR ready for review.