1. Supported date ranges are 30 / 90 days ago. The default is 90 days
ago.
2. All issues created before "x days ago" are filtered out, even if they
have other related data (test runs, merge requests) within the filter
range.
1. Pass in an array of queries - the first to return a value will be
used. This makes it easier to add more heuristics later.
2. Convert all queries with 'or' in the title to two separate queries.
3. Rename all `mr_` methods to `merge_request_`
1. Rewrite the `Queries` module to work off a `data_point` hash, with
`issue` and `merge_request` as keys. The "production" query needs
both an issue and a merge request to make it's calculation, so it
makes sense to keep things consistent and provide the same
data (issue + merge request) for all queries.
1. Record the `wip_flag_first_removed_at` and
`first_assigned_to_user_other_than_author` metrics for a merge
request. Use a `merge_request_metrics` table, similar to the one for
`issues`. Metrics are recorded `after_save`.
2. Move larger queries to a `CycleAnalytics::Queries` module.
