Frontend: Remove `mixins/timeago.js` and move its logic to pipelines_list/time_ago.vue
Problem
The logic of our duration/"started at" column in the pipelines list is spread over two files:
app/assets/javascripts/pipelines/components/pipelines_list/time_ago.vueapp/assets/javascripts/vue_shared/mixins/timeago.js
Note: Actually this is widely used.mixins/timeago.js is not used anywhere else.
Proposal
Move the logic of the mixin into the component.
Bonus: durationFormatted() could be moved to datetime_utility.js to improve its testability and use a more functional approach.
Edited by Mark Nuzzo
