Add a merge request template.

This automatically adds the Needs Review label to new merge requests,
and also gives a basic formalities and required info list.

cc: @rempt, @DKazakov

Author: therahedwig

.gitlab/merge_request_templates/merge_request_template.md

@@ -0,0 +1,18 @@
+(Tell us what you did!)
+
+Test Plan
+---------
+
+(Tell us how to test the changes you made.)
+
+Formalities Checklist
+--------------------- 
+
+- [ ] I confirmed this builds.
+- [ ] I confirmed Krita ran and the relevant functions work.
+- [ ] I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
+- [ ] I made sure my commits build individually and have good descriptions as per [KDE guidelines](https://community.kde.org/Policies/Commit_Policy).
+- [ ] I made sure my code conforms to the standards set in the HACKING file.
+- [ ] I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per [KDE Licensing Policy](https://community.kde.org/Policies/Licensing_Policy).
+
+/label ~"Needs Review"