This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
* FEATURE: Add `IgnoredUsersSummary` daily job
## Why?
This is part of the [Ability to ignore a user feature](https://meta.discourse.org/t/ability-to-ignore-a-user/110254/8).
We want to:
1. Send an automatic group PM that goes out to moderators
2. When {x} users have Ignored the same user, threshold defined by a site setting, default of 5
3. Only send this message every X days which is defined by another site setting
Sam Saffron
Tarek Khalil