cookstyle CHEF-24885 - Replace CONTRIBUTING.md file with standard template for workstation

Replace CONTRIBUTING.md file with standard template for workstation

This pull request replaces the existing CONTRIBUTING.md file with the standard template for the workstation project. As part of the repo standardization effort we are replacing all the different contributing guides with a standard template that links to a published version of the chef-oss-practices repo.

This PR is intended to be a mere mechanical change, not a change in policy. Watch chef/chef-oss-practices for changes in policy.

The link provided in the template may not function at the time this PR is opened, in which case this PR is intended to remain in Draft status if the repo permits; in any case it should not be merged until the link is live.