This will return data containing time tracked
for the group issues by group members and within
a time frame (limited to 60 days)

To get the collection of timelogs for a certain
group we include in Group a new concern
HasTimelogsReport that will use Timelog scopes
to filter results.

We use a TimelogPresenter to display additional
fields in TimelogType

Group timelogs is a premium feature so we added
group_timelogs feature to license

TimelogType is authorized with read_group_timelogs
permission that checks for a minimun access level of
reporter and group_timelogs feature being available
Refactor changes to improve code quality

- Include subgroups in Issue and Timelog scopes
- Field timelogs in GroupType is never null
- Add error to object validation in TimelogResolver
- Use fields UserType and IssueType  in TimelogType
- Improve rule in GroupPolicy
- Remove redundant TimelogPresenter
- Add missing specs for new scopes
- Extend specs for GroupType and  TimelogType
- Add new matcher fon non null graphql fields

Update GraphQL schema
Add index for spent_at in timelogs table

Fix Timelog scope to use group descendants