chore(github): Suspend GitHub Discussions Ideas and revert to feature…

… request issues (#4153)

# Description

## Problem\*

The move towards using GitHub Discussions to suggest ideas was found
premature following #2672, as it
introduced additional frictions in:
- Requiring the need to switch between Issues / Discussions to distill
ideas raised
- Discussions are not manageable on GitHub's Project Board

## Summary\*

Until we can formally define how the Ideas section in GitHub Discussions
should be used, this PR reverts the repo back to using GitHub Issues for
feature requests for us to move faster in the meantime.

## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [ ] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

.github/ISSUE_TEMPLATE/idea_action_plan.yml → .github/ISSUE_TEMPLATE/feature_request.yml

@@ -1,5 +1,5 @@
-name: Idea Action Plan
-description: Outline the scope and steps for implementing an enhancement. Start with "Ideas" instead to request and discuss new features.
+name: Feature Request
+description: Suggest an idea for this project.
 labels: ["enhancement"]
 body:
   - type: markdown