docs: Refactor ISSUE_TEMPLATEs to use GitHub issue forms

[erikmd]

• Kind: enhancement

Description

Refactor .github/ISSUE_TEMPLATES/* to use issue forms:

https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/syntax-for-issue-forms

Checklist

• Read the CONTRIBUTING.md guide and:
  • Use Atomic Commits so each commit gathers a single logical change
  • Use Conventional Commits regarding commit messages (needed by our release toolchain)

Note to maintainers

• Read this wiki page
• Make sure the PR has a milestone
• Assign yourself before merging
• We can squash-merge 1-commit PRs (use a header with a conventional-commit type, add a footer with Fix #… if need be)

[erikmd]

Merging now as the refactored version has already been tested on a separated repo.