Ability to select a default issue or merge request template from `.gitlab/*templates`

Problem to solve

Currently, the default templates are not version controlled in the repository along with the other templates available in .gitlab/*templates. If those directories are properly populated, one of them should be able to be chosen as the default template instead of using the text box in the project settings.

Target audience

• Parker, Product Manager, https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas#parker-product-manager

• Delaney, Development Team Lead, https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas#delaney-development-team-lead

• Sasha, Software Developer, https://about.gitlab.com/handbook/marketing/product-marketing/roles-personas#sasha-software-developer

Further details

Currently only Maintainers and Owners can change the default templates in the project settings, even though developers and others (for public projects) can contribute changes all other templates through the usual development and MR processes.

A project could manage a default template and follow manual steps to copy and paste into the

Proposal

If there are templates available, provide a way to choose one instead of using the text field.

Another option may be to specify a specific named path that will be used by default if present, such as .gitlab/issue_templates/default.md and .gitlab/merge_request_details.md.

Documentation

The documentation for [setting default templates will need to be updated for the new controls](https://docs.gitlab.com/ee/user/project/description_templates.html#setting-a-default-template-for-issues-and-merge-requests--starter

What does success look like, and how can we measure that?

We will see updates to the default templates submitted as merge requests, with more team members contributing to them.

Links / references