Add fourmolu code formatter

[kderme]

Merge #1332 first

[jbgi]

would a fourmolu.yaml config be clearer? would also permit to use fourmolu safely outside of this script.
Also cardano-ledger adopted fourmolu recently: https://github.com/input-output-hk/cardano-ledger/blob/master/fourmolu.yaml
so I'm wondering if a uniform fourmolu config across project would be easier for people working on multiple project?

[kderme]

The config file definitely makes sence.
The only difference I see with leger is the record-brace-space, for which I use the default false
I'm ok with these diffs, so I'll adopt it

-        throwIO err404{errBody = encode err}
+        throwIO err404 {errBody = encode err}

-  toJSON failure@DbLookupPoolMetadataHash{} =
+  toJSON failure@DbLookupPoolMetadataHash {} =