Track your time in the same tool you do your work

Introduced Time Tracking functionality to GitLab Enterprise Edition (available for free on GitLab.com during beta). This feature allows users to record time spent on tasks and set time estimates directly within issues and merge requests using `/spend` and `/estimate` slash commands. Multiple `/spend` commands aggregate into a total time spent visible in the sidebar, while the last `/estimate` command overrides previous ones. This aims to reduce reliance on external time tracking tools.