add Account Request issue template

Signed-off-by: Kevin Morris <kevr@0cost.org>

.gitlab/issue_templates/Account Request.md

+## Checklist
+
+- [ ] I have set a Username in the Details section
+- [ ] I have set an Email in the Details section
+- [ ] I have set a valid Account Type in the Details section
+
+## Details
+
+- Instance: aur-dev.archlinux.org
+- Username: the_username_you_want
+- Email: valid@email.org
+- Account Type: (User|Trusted User)