Support tomato as time measurement unit in Time Tracking

Description

When using GitLab's time tracking, I would like to be able to specify task estimate and duration in tomatoes, as it is a more generic and stable form of measuring productive time.

Proposal

Add a t measurement unit:

  • weeks (w)
  • days (d)
  • hours (h)
  • minutes (m)
  • tomatoes (t)

Usually 1t equals to 25m, but this can vary as each team might want to adjust how many minutes a tomato represents for them.

For my use case, my team would only use tomatoes to measure time, so no relationship to minutes is necessary, given that we will be comparing only tomatoes to tomatoes.

Links / references

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.