This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
* 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