Resolve "Ajouter un ou plusieurs modèles de ticket Gitlab : fonctionnalité, bug, ..."

Closes #24

See merge request !2

see: https://docs.gitlab.com/ee/user/project/description_templates.html#set-a-default-template-for-merge-requests-and-issues

see: https://docs.gitlab.com/ee/user/project/description_templates.html#set-a-default-template-for-merge-requests-and-issues

CHORE: add technical files (.gitinore, .gitattributes, .editorconfig and Gitlab templates: issue, MR)