[RFC]: Add slash command for posting a PR-specific command comment

[Planeshifter]

This RFC proposes adding a new slash command /stdlib commands-comment that automatically generates and posts PR-specific build and test commands as a comment from the @stdlib-bot. This will help streamline the PR review process by providing contributors with the exact commands needed to build, test, and benchmark their changes.

The slash command should:

• Automatically detect the package path from the PR's changed files

• Generate the appropriate make commands for:

  • Building native add-ons
  • Running C examples
  • Running C benchmarks
  • Running JavaScript examples
  • Running JavaScript benchmarks
  • Running tests

In the new GitHub actions workflow for this slash command, we will need to Implement logic to:

• Identify changed package paths
• Generate appropriate command strings based on package path
• Format commands in markdown
• Post formatted comment via GitHub API

One open question is how to handle the case when multiple packages are modified in one PR.

Time estimate without AI: 4h.
Time estimate with AI: 3h.

[Planeshifter]

PR-URL: stdlib-js/stdlib#5640

Loom recordings:

https://www.loom.com/share/0eed756a8c6f47248f9b5d8f0f465aab?sid=9c986bed-4dca-49a3-b908-30fff83d83ef
https://www.loom.com/share/229adff5189e44f991e8dd2c6b2e7250?sid=6f021ac9-5985-4536-aced-d1143feeba70
https://www.loom.com/share/34840cb5aecb4753b3d7cdb4c59c72a8?sid=c00f917f-6b14-42e7-bd4e-54c8176e9bd6

Time to initial completion: 1h 45min

[Planeshifter]

Notes: Scoped it down a little to not handle case of multiple packages touched in a single PR. Work went decently smoothly; it was a great help that we have already done most of the operations needed for it to work somewhere else in the codebase, so I could often orient myself on what's already there.