chore: use rendered issue templates

[zimeg]

Summary

This PR updates the issue templates to use a rendered format with placeholders for markdown sections 👾

Preview

This reflects the current changes on main branch:

👁️‍🗨️ https://github.com/slackapi/node-slack-sdk/issues/new/choose

Notes

📚 https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 24df7fc

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.17%. Comparing base (59df200) to head (24df7fc).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2518   +/-   ##
=======================================
  Coverage   93.17%   93.17%           
=======================================
  Files          40       40           
  Lines       11384    11384           
  Branches      726      726           
=======================================
  Hits        10607    10607           
  Misses        765      765           
  Partials       12       12           

Flag	Coverage Δ
cli-hooks	95.42% <ø> (ø)
cli-test	94.79% <ø> (ø)
oauth	77.39% <ø> (ø)
socket-mode	61.87% <ø> (ø)
web-api	98.12% <ø> (ø)
webhook	96.66% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[zimeg]

🪬 A note for the kind reviewers!

[zimeg]

🤖 note: This checkbox motivated the changes following. IIRC this is @slack/webhook instead.

[zimeg]

📝 note: The config.yml file is significant and separate from other orderings made above. Contact links will continue appear at the end of options, but we now suggest the following issues:

1. Question
2. Bug
3. Feature
4. Documentation

🐢 ✨

[zimeg]

🪓 note: The top-level issue_template.md is noted as legacy and was used if blank issues were allowed. No change should be noticed after removing this!

[zimeg]

@WilliamBergamin I appreciate your reviews toward improved developer experiences even in opening issues 💌 ✨

Let's merge this now - I'll follow up with screenshots if all goes well. And we might consider extending this to adjacent projects in the next few weeks IMHO but I might save this for when I'm bored again 😉

[zimeg]

📸 **Question**

📸 **Bug**

📸 **Enhancement**

📸 **Document**