This pull request adds a new GitHub Actions workflow to automate
reviewer assignment for pull requests. The workflow leverages the
`codeowner-coordinator` repository to intelligently assign the most
relevant teams as reviewers based on the changes in the PR. This should
streamline the review process and ensure the right teams are notified.

**Automated Reviewer Assignment Workflow:**

* Introduced `.github/workflows/assign-reviewers.yml`, a workflow that
triggers on PR open and ready-for-review events to assign 1-2 relevant
teams as reviewers using a script from the
`zed-industries/codeowner-coordinator` repository.
* The workflow checks out the coordinator repo, sets up Python, installs
dependencies, and runs the assignment script with the necessary
environment variables.
* Reviewer assignment is only performed for PRs originating from within
the organization for now.
* The output of the reviewer assignment step is maintained as an Actions
artifact for later inspection or debugging.

Closes #ISSUE

Before you mark this PR as ready for review, make sure that you have:
- [ ] ~~Added a solid test coverage and/or screenshots from doing manual
testing~~
- [x] Done a self-review taking into account security and performance
aspects
- [ ] ~~Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)~~

Release Notes:

- N/A