Add issue templates
See the Gitlab docs: https://docs.gitlab.com/ee/user/project/description_templates.html and Gitlab's own examples: https://gitlab.com/gitlab-org/gitlab/-/tree/master/.gitlab/issue_templates
See the Gitlab docs: https://docs.gitlab.com/ee/user/project/description_templates.html and Gitlab's own examples: https://gitlab.com/gitlab-org/gitlab/-/tree/master/.gitlab/issue_templates