Display selected timezone on user's profile
In https://gitlab.com/gitlab-org/gitlab/-/issues/15137 we added a timezone dropdown when editing your profile. The timezone is not yet displayed anywhere yet. We should display the timezone on the user's profile.
| Before | After |
| ------ | ------ |
|  |  |
## Implementation plan
1. Create a `local_time` helper in [app/helpers/time_zone_helper.rb](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/helpers/time_zone_helper.rb)
```ruby
def local_time(timezone)
time_with_zone_instance = ActiveSupport::TimeZone.new(timezone).now
offset = time_with_zone_instance.utc_offset
formatted_offset = offset / 3600
time_with_zone_instance.strftime("%H:%M (UTC#{formatted_offset})")
end
```
2. Use that helper in [app/views/users/show.html.haml#L75](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/views/users/show.html.haml#L75)
3. Add a feature spec in [spec/features/users/show_spec.rb](https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/features/users/show_spec.rb)
issue