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.
Timothy Andrew