* Stop the config being global (in almost all contexts).
* make sure unit test has a config
* Make failing word list more visible
* Only use Healthz from index.ts
Not really sure how useful it is anyways?
Towards opinions in PolicyLists.
This changeset is part of an ongoing effort to implement "opinions"
within policy lists, as per MSC3847.
For the time being:
- we rename BanList into PolicyList;
- we cleanup a little dead code;
- we replace a few `string`s with `enum`;
- `ListRule` becomes an abstract class with two concrete subclasses `ListRuleBan` and `ListRuleOpinion`.
