Ask for a field per line in a record value
A new module rule, `HsRecordFieldPerLine`.
## Why
Changing one field of a record written on one line rewrites that line, so the
diff says the whole value changed and review has to read it to find out what
did. Adding a field reflows whatever followed it. A field per line makes each of
those a one-line diff.
A value with one field has nothing to line up against and no second field to
push around, so it is left alone.
## What it reads
The fact is the offending value rather than every record value. What it records
is the line each field starts on, not the expression's own span: a field whose
value runs onto a second line makes the expression multi-line while every field
still has a line of its own, and that is not what the rule is about. The `..` of
a wildcard stands where a field would, so it takes up a line the same way.
Both `RecordCon` and `RecordUpd` are read, and both update forms. Record
patterns are not record values and are left alone.
## The two commits
1. The rule: the check, the registry entry, the good and bad resources.
2. This repository written to keep it. The flake runs hopinion on hopinion, so
a rule that ships is one this repository keeps. Layout only, 19 files.
`nix flake check` passes.