Add the arclint file in kwayland

Summary:
- xml linter to make sure that we don't add broken protocols
- merge-conflict so that we don't commit merge-conflict markers
- spell check for documentation
- cppcheck to check the code

Test Plan: broke some files manually, and then ran arc lint

Reviewers: #frameworks, mart

Reviewed By: mart

Subscribers: kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D13533